Merge pull request #603 from tomaka/gl-attribs

Separate the builder attributes into multiple substates

20 files changed, 475 insertions, 337 deletions

diff --git a/src/api/android/mod.rs b/src/api/android/mod.rs
index 0f770c2..be5a79f 100644
--- a/src/api/android/mod.rs
+++ b/src/api/android/mod.rs
@@ -14,12 +14,14 @@ use events::MouseButton;
 use std::collections::VecDeque;
 
 use Api;
-use BuilderAttribs;
 use ContextError;
 use CursorState;
+use GlAttributes;
 use GlContext;
 use GlRequest;
 use PixelFormat;
+use PixelFormatRequirements;
+use WindowAttributes;
 use native_monitor::NativeMonitorId;
 
 use api::egl;
@@ -104,15 +106,20 @@ impl<'a> Iterator for WaitEventsIterator<'a> {
 }
 
 impl Window {
-    pub fn new(builder: BuilderAttribs) -> Result<Window, CreationError> {
+    pub fn new(win_attribs: &WindowAttributes, pf_reqs: &PixelFormatRequirements,
+               opengl: &GlAttributes<&Window>) -> Result<Window, CreationError>
+    {
         use std::{mem, ptr};
 
+        let opengl = opengl.clone().map_sharing(|w| &w.context);
+
         let native_window = unsafe { android_glue::get_native_window() };
         if native_window.is_null() {
             return Err(OsError(format!("Android's native window is null")));
         }
 
-        let context = try!(EglContext::new(egl::ffi::egl::Egl, &builder, egl::NativeDisplay::Android)
+        let context = try!(EglContext::new(egl::ffi::egl::Egl, pf_reqs, &opengl,
+                                           egl::NativeDisplay::Android)
                                                 .and_then(|p| p.finish(native_window as *const _)));
 
         let (tx, rx) = channel();
@@ -254,9 +261,13 @@ pub struct HeadlessContext(EglContext);
 
 impl HeadlessContext {
     /// See the docs in the crate root file.
-    pub fn new(builder: BuilderAttribs) -> Result<HeadlessContext, CreationError> {
-        let context = try!(EglContext::new(egl::ffi::egl::Egl, &builder, egl::NativeDisplay::Android));
-        let context = try!(context.finish_pbuffer());
+    pub fn new(dimensions: (u32, u32), pf_reqs: &PixelFormatRequirements,
+               opengl: &GlAttributes<&HeadlessContext>) -> Result<HeadlessContext, CreationError>
+    {
+        let opengl = opengl.clone().map_sharing(|c| &c.0);
+        let context = try!(EglContext::new(egl::ffi::egl::Egl, pf_reqs, &opengl,
+                           egl::NativeDisplay::Android));
+        let context = try!(context.finish_pbuffer(dimensions));     // TODO: 
         Ok(HeadlessContext(context))
     }
 }
diff --git a/src/api/caca/mod.rs b/src/api/caca/mod.rs
index 3b4018e..c1a19c7 100644
--- a/src/api/caca/mod.rs
+++ b/src/api/caca/mod.rs
@@ -5,14 +5,16 @@ use libc;
 use api::osmesa::{OsMesaContext, OsMesaCreationError};
 
 use Api;
-use BuilderAttribs;
 use ContextError;
 use CreationError;
 use Event;
+use GlAttributes;
 use GlContext;
 use PixelFormat;
+use PixelFormatRequirements;
 use CursorState;
 use MouseCursor;
+use WindowAttributes;
 
 use std::collections::VecDeque;
 use std::path::Path;
@@ -84,8 +86,14 @@ impl<'a> Iterator for WaitEventsIterator<'a> {
 }
 
 impl Window {
-    pub fn new(builder: BuilderAttribs) -> Result<Window, CreationError> {
-        let opengl = match OsMesaContext::new(builder) {
+    pub fn new(window: &WindowAttributes, pf_reqs: &PixelFormatRequirements,
+               opengl: &GlAttributes<&Window>) -> Result<Window, CreationError>
+    {
+        let opengl = opengl.clone().map_sharing(|w| &w.opengl);
+
+        let opengl = match OsMesaContext::new(window.dimensions.unwrap_or((800, 600)), pf_reqs,
+                                              &opengl)
+        {
             Err(OsMesaCreationError::NotSupported) => return Err(CreationError::NotSupported),
             Err(OsMesaCreationError::CreationError(e)) => return Err(e),
             Ok(c) => c
diff --git a/src/api/cocoa/headless.rs b/src/api/cocoa/headless.rs
index 7cd0f88..f9bbffd 100644
--- a/src/api/cocoa/headless.rs
+++ b/src/api/cocoa/headless.rs
@@ -1,8 +1,9 @@
 use ContextError;
 use CreationError;
 use CreationError::OsError;
-use BuilderAttribs;
+use GlAttributes;
 use GlContext;
+use PixelFormatRequirements;
 use libc;
 use std::ptr;
 
@@ -27,8 +28,9 @@ pub struct HeadlessContext {
 }
 
 impl HeadlessContext {
-    pub fn new(builder: BuilderAttribs) -> Result<HeadlessContext, CreationError> {
-        let (width, height) = builder.dimensions.unwrap_or((1024, 768));
+    pub fn new((width, height): (u32, u32), pf_reqs: &PixelFormatRequirements,
+               opengl: &GlAttributes<&HeadlessContext>) -> Result<HeadlessContext, CreationError>
+    {
         let context = unsafe {
             let attributes = [
                 NSOpenGLPFAAccelerated as u32,
diff --git a/src/api/cocoa/mod.rs b/src/api/cocoa/mod.rs
index 259f847..539545c 100644
--- a/src/api/cocoa/mod.rs
+++ b/src/api/cocoa/mod.rs
@@ -7,13 +7,15 @@ use CreationError::OsError;
 use libc;
 
 use Api;
-use BuilderAttribs;
 use ContextError;
+use GlAttributes;
 use GlContext;
 use GlProfile;
 use GlRequest;
 use PixelFormat;
+use PixelFormatRequirements;
 use Robustness;
+use WindowAttributes;
 use native_monitor::NativeMonitorId;
 
 use objc::runtime::{Class, Object, Sel, BOOL, YES, NO};
@@ -266,12 +268,14 @@ impl<'a> Iterator for WaitEventsIterator<'a> {
 
 impl Window {
     #[cfg(feature = "window")]
-    pub fn new(builder: BuilderAttribs) -> Result<Window, CreationError> {
-        if builder.sharing.is_some() {
+    pub fn new(win_attribs: &WindowAttributes, pf_reqs: &PixelFormatRequirements,
+               opengl: &GlAttributes<&Window>) -> Result<Window, CreationError>
+    {
+        if opengl.sharing.is_some() {
             unimplemented!()
         }
 
-        match builder.gl_robustness {
+        match opengl.robustness {
             Robustness::RobustNoResetNotification | Robustness::RobustLoseContextOnReset => {
                 return Err(CreationError::RobustnessNotSupported);
             },
@@ -283,7 +287,7 @@ impl Window {
             None      => { return Err(OsError(format!("Couldn't create NSApplication"))); },
         };
 
-        let window = match Window::create_window(&builder)
+        let window = match Window::create_window(win_attribs)
         {
             Some(window) => window,
             None         => { return Err(OsError(format!("Couldn't create NSWindow"))); },
@@ -295,13 +299,13 @@ impl Window {
 
         // TODO: perhaps we should return error from create_context so we can
         // determine the cause of failure and possibly recover?
-        let (context, pf) = match Window::create_context(*view, &builder) {
+        let (context, pf) = match Window::create_context(*view, pf_reqs, opengl) {
             Ok((context, pf)) => (context, pf),
             Err(e) => { return Err(OsError(format!("Couldn't create OpenGL context: {}", e))); },
         };
 
         unsafe {
-            if builder.transparent {
+            if win_attribs.transparent {
                 let clear_col = {
                     let cls = Class::get("NSColor").unwrap();
 
@@ -317,7 +321,7 @@ impl Window {
             }
             
             app.activateIgnoringOtherApps_(YES);
-            if builder.visible {
+            if win_attribs.visible {
                 window.makeKeyAndOrderFront_(nil);
             } else {
                 window.makeKeyWindow();
@@ -356,9 +360,9 @@ impl Window {
         }
     }
 
-    fn create_window(builder: &BuilderAttribs) -> Option<IdRef> {
+    fn create_window(attrs: &WindowAttributes) -> Option<IdRef> {
         unsafe { 
-            let screen = match builder.monitor {
+            let screen = match attrs.monitor {
                 Some(ref monitor_id) => {
                     let native_id = match monitor_id.get_native_identifier() {
                         NativeMonitorId::Numeric(num) => num,
@@ -390,12 +394,12 @@ impl Window {
             let frame = match screen {
                 Some(screen) => NSScreen::frame(screen),
                 None => {
-                    let (width, height) = builder.dimensions.unwrap_or((800, 600));
+                    let (width, height) = attrs.dimensions.unwrap_or((800, 600));
                     NSRect::new(NSPoint::new(0., 0.), NSSize::new(width as f64, height as f64))
                 }
             };
 
-            let masks = if screen.is_some() || !builder.decorations {
+            let masks = if screen.is_some() || !attrs.decorations {
                 NSBorderlessWindowMask as NSUInteger |
                 NSResizableWindowMask as NSUInteger
             } else {
@@ -412,7 +416,7 @@ impl Window {
                 NO,
             ));
             window.non_nil().map(|window| {
-                let title = IdRef::new(NSString::alloc(nil).init_str(&builder.title));
+                let title = IdRef::new(NSString::alloc(nil).init_str(&attrs.title));
                 window.setTitle_(*title);
                 window.setAcceptsMouseMovedEvents_(YES);
                 if screen.is_some() {
@@ -437,8 +441,10 @@ impl Window {
         }
     }
 
-    fn create_context(view: id, builder: &BuilderAttribs) -> Result<(IdRef, PixelFormat), CreationError> {
-        let profile = match (builder.gl_version, builder.gl_version.to_gl_version(), builder.gl_profile) {
+    fn create_context(view: id, pf_reqs: &PixelFormatRequirements, opengl: &GlAttributes<&Window>)
+                      -> Result<(IdRef, PixelFormat), CreationError>
+    {
+        let profile = match (opengl.version, opengl.version.to_gl_version(), opengl.profile) {
 
             // Note: we are not using ranges because of a rust bug that should be fixed here:
             // https://github.com/rust-lang/rust/pull/27050
@@ -471,16 +477,16 @@ impl Window {
         // full color size and hope for the best. Another hiccup is that
         // `NSOpenGLPFAColorSize` also includes `NSOpenGLPFAAlphaSize`,
         // so we have to account for that as well.
-        let alpha_depth = builder.alpha_bits.unwrap_or(8);
-        let color_depth = builder.color_bits.unwrap_or(24) + alpha_depth;
+        let alpha_depth = pf_reqs.alpha_bits.unwrap_or(8);
+        let color_depth = pf_reqs.color_bits.unwrap_or(24) + alpha_depth;
 
         let mut attributes = vec![
             NSOpenGLPFADoubleBuffer as u32,
             NSOpenGLPFAClosestPolicy as u32,
             NSOpenGLPFAColorSize as u32, color_depth as u32,
             NSOpenGLPFAAlphaSize as u32, alpha_depth as u32,
-            NSOpenGLPFADepthSize as u32, builder.depth_bits.unwrap_or(24) as u32,
-            NSOpenGLPFAStencilSize as u32, builder.stencil_bits.unwrap_or(8) as u32,
+            NSOpenGLPFADepthSize as u32, pf_reqs.depth_bits.unwrap_or(24) as u32,
+            NSOpenGLPFAStencilSize as u32, pf_reqs.stencil_bits.unwrap_or(8) as u32,
             NSOpenGLPFAOpenGLProfile as u32, profile,
         ];
 
@@ -491,7 +497,7 @@ impl Window {
             attributes.push(NSOpenGLPFAColorFloat as u32);
         }
 
-        builder.multisampling.map(|samples| {
+        pf_reqs.multisampling.map(|samples| {
             attributes.push(NSOpenGLPFAMultisample as u32);
             attributes.push(NSOpenGLPFASampleBuffers as u32); attributes.push(1);
             attributes.push(NSOpenGLPFASamples as u32); attributes.push(samples as u32);
@@ -540,7 +546,7 @@ impl Window {
                     };
 
                     cxt.setView_(view);
-                    let value = if builder.vsync { 1 } else { 0 };
+                    let value = if opengl.vsync { 1 } else { 0 };
                     cxt.setValues_forParameter_(&value, NSOpenGLContextParameter::NSOpenGLCPSwapInterval);
 
                     CGLEnable(cxt.CGLContextObj(), kCGLCECrashOnRemovedFunctions);
diff --git a/src/api/egl/mod.rs b/src/api/egl/mod.rs
index 4cd7a7c..56b709d 100644
--- a/src/api/egl/mod.rs
+++ b/src/api/egl/mod.rs
@@ -2,12 +2,13 @@
            target_os = "dragonfly", target_os = "freebsd"))]
 #![allow(unused_variables)]
 
-use BuilderAttribs;
 use ContextError;
 use CreationError;
+use GlAttributes;
 use GlContext;
 use GlRequest;
 use PixelFormat;
+use PixelFormatRequirements;
 use Robustness;
 use Api;
 
@@ -158,11 +159,11 @@ impl Context {
     /// This function initializes some things and chooses the pixel format.
     ///
     /// To finish the process, you must call `.finish(window)` on the `ContextPrototype`.
-    pub fn new<'a>(egl: ffi::egl::Egl, builder: &'a BuilderAttribs<'a>,
-                   native_display: NativeDisplay)
+    pub fn new<'a>(egl: ffi::egl::Egl, pf_reqs: &PixelFormatRequirements,
+                   opengl: &'a GlAttributes<&'a Context>, native_display: NativeDisplay)
                    -> Result<ContextPrototype<'a>, CreationError>
     {
-        if builder.sharing.is_some() {
+        if opengl.sharing.is_some() {
             unimplemented!()
         }
 
@@ -197,7 +198,7 @@ impl Context {
 
         // binding the right API and choosing the version
         let (version, api) = unsafe {
-            match builder.gl_version {
+            match opengl.version {
                 GlRequest::Latest => {
                     if egl_version >= (1, 4) {
                         if egl.BindAPI(ffi::egl::OPENGL_API) != 0 {
@@ -246,10 +247,10 @@ impl Context {
         };
 
         let configs = unsafe { try!(enumerate_configs(&egl, display, &egl_version, api, version)) };
-        let (config_id, pixel_format) = try!(builder.choose_pixel_format(configs.into_iter()));
+        let (config_id, pixel_format) = try!(pf_reqs.choose_pixel_format(configs.into_iter()));
 
         Ok(ContextPrototype {
-            builder: builder,
+            opengl: opengl,
             egl: egl,
             display: display,
             egl_version: egl_version,
@@ -330,7 +331,7 @@ impl Drop for Context {
 }
 
 pub struct ContextPrototype<'a> {
-    builder: &'a BuilderAttribs<'a>,
+    opengl: &'a GlAttributes<&'a Context>,
     egl: ffi::egl::Egl,
     display: ffi::egl::types::EGLDisplay,
     egl_version: (ffi::egl::types::EGLint, ffi::egl::types::EGLint),
@@ -366,9 +367,7 @@ impl<'a> ContextPrototype<'a> {
         self.finish_impl(surface)
     }
 
-    pub fn finish_pbuffer(self) -> Result<Context, CreationError> {
-        let dimensions = self.builder.dimensions.unwrap_or((800, 600));
-
+    pub fn finish_pbuffer(self, dimensions: (u32, u32)) -> Result<Context, CreationError> {
         let attrs = &[
             ffi::egl::WIDTH as libc::c_int, dimensions.0 as libc::c_int,
             ffi::egl::HEIGHT as libc::c_int, dimensions.1 as libc::c_int,
@@ -394,18 +393,18 @@ impl<'a> ContextPrototype<'a> {
             if let Some(version) = self.version {
                 try!(create_context(&self.egl, self.display, &self.egl_version,
                                     &self.extensions, self.api, version, self.config_id,
-                                    self.builder.gl_debug, self.builder.gl_robustness))
+                                    self.opengl.debug, self.opengl.robustness))
 
             } else if self.api == Api::OpenGlEs {
                 if let Ok(ctxt) = create_context(&self.egl, self.display, &self.egl_version,
                                                  &self.extensions, self.api, (2, 0), self.config_id,
-                                                 self.builder.gl_debug, self.builder.gl_robustness)
+                                                 self.opengl.debug, self.opengl.robustness)
                 {
                     ctxt
                 } else if let Ok(ctxt) = create_context(&self.egl, self.display, &self.egl_version,
                                                         &self.extensions, self.api, (1, 0),
-                                                        self.config_id, self.builder.gl_debug,
-                                                        self.builder.gl_robustness)
+                                                        self.config_id, self.opengl.debug,
+                                                        self.opengl.robustness)
                 {
                     ctxt
                 } else {
@@ -415,19 +414,19 @@ impl<'a> ContextPrototype<'a> {
             } else {
                 if let Ok(ctxt) = create_context(&self.egl, self.display, &self.egl_version,
                                                  &self.extensions, self.api, (3, 2), self.config_id,
-                                                 self.builder.gl_debug, self.builder.gl_robustness)
+                                                 self.opengl.debug, self.opengl.robustness)
                 {
                     ctxt
                 } else if let Ok(ctxt) = create_context(&self.egl, self.display, &self.egl_version,
                                                         &self.extensions, self.api, (3, 1),
-                                                        self.config_id, self.builder.gl_debug,
-                                                        self.builder.gl_robustness)
+                                                        self.config_id, self.opengl.debug,
+                                                        self.opengl.robustness)
                 {
                     ctxt
                 } else if let Ok(ctxt) = create_context(&self.egl, self.display, &self.egl_version,
                                                         &self.extensions, self.api, (1, 0),
-                                                        self.config_id, self.builder.gl_debug,
-                                                        self.builder.gl_robustness)
+                                                        self.config_id, self.opengl.debug,
+                                                        self.opengl.robustness)
                 {
                     ctxt
                 } else {
diff --git a/src/api/emscripten/mod.rs b/src/api/emscripten/mod.rs
index 79dda6b..e6f51e3 100644
--- a/src/api/emscripten/mod.rs
+++ b/src/api/emscripten/mod.rs
@@ -83,7 +83,7 @@ impl Window {
 
         // setting the attributes
         // FIXME: 
-        /*match builder.gl_version {
+        /*match builder.opengl.version {
             Some((major, minor)) => {
                 attributes.majorVersion = major as libc::c_int;
                 attributes.minorVersion = minor as libc::c_int;
diff --git a/src/api/glx/mod.rs b/src/api/glx/mod.rs
index a1ee092..7f54760 100644
--- a/src/api/glx/mod.rs
+++ b/src/api/glx/mod.rs
@@ -1,13 +1,14 @@
 #![cfg(all(any(target_os = "linux", target_os = "dragonfly", target_os = "freebsd"), feature = "window"))]
 
-use BuilderAttribs;
 use ContextError;
 use CreationError;
+use GlAttributes;
 use GlContext;
 use GlProfile;
 use GlRequest;
 use Api;
 use PixelFormat;
+use PixelFormatRequirements;
 use Robustness;
 
 use libc;
@@ -34,14 +35,14 @@ fn with_c_str<F, T>(s: &str, f: F) -> T where F: FnOnce(*const libc::c_char) ->
 }
 
 impl Context {
-    pub fn new<'a>(glx: ffi::glx::Glx, xlib: &ffi::Xlib, builder: &'a BuilderAttribs<'a>,
-                   display: *mut ffi::Display)
+    pub fn new<'a>(glx: ffi::glx::Glx, xlib: &ffi::Xlib, pf_reqs: &PixelFormatRequirements,
+                   opengl: &'a GlAttributes<&'a Context>, display: *mut ffi::Display)
                    -> Result<ContextPrototype<'a>, CreationError>
     {
         // finding the pixel format we want
         let (fb_config, pixel_format) = {
             let configs = unsafe { try!(enumerate_configs(&glx, xlib, display)) };
-            try!(builder.choose_pixel_format(configs.into_iter()))
+            try!(pf_reqs.choose_pixel_format(configs.into_iter()))
         };
 
         // getting the visual infos
@@ -57,7 +58,7 @@ impl Context {
 
         Ok(ContextPrototype {
             glx: glx,
-            builder: builder,
+            opengl: opengl,
             display: display,
             fb_config: fb_config,
             visual_infos: unsafe { mem::transmute(visual_infos) },
@@ -120,7 +121,7 @@ impl Drop for Context {
 
 pub struct ContextPrototype<'a> {
     glx: ffi::glx::Glx,
-    builder: &'a BuilderAttribs<'a>,
+    opengl: &'a GlAttributes<&'a Context>,
     display: *mut ffi::Display,
     fb_config: ffi::glx::types::GLXFBConfig,
     visual_infos: ffi::XVisualInfo,
@@ -133,16 +134,9 @@ impl<'a> ContextPrototype<'a> {
     }
 
     pub fn finish(self, window: ffi::Window) -> Result<Context, CreationError> {
-        let share = if let Some(win) = self.builder.sharing {
-            match win {
-                &PlatformWindow::X(ref win) => match win.x.context {
-                    ::api::x11::Context::Glx(ref c) => c.context,
-                    _ => panic!("Cannot share contexts between different APIs")
-                },
-                _ => panic!("Cannot use glx on a non-X11 window.")
-            }
-        } else {
-            ptr::null()
+        let share = match self.opengl.sharing {
+            Some(ctxt) => ctxt.context,
+            None => ptr::null()
         };
 
         // loading the list of extensions
@@ -160,46 +154,46 @@ impl<'a> ContextPrototype<'a> {
         });
 
         // creating GL context
-        let context = match self.builder.gl_version {
+        let context = match self.opengl.version {
             GlRequest::Latest => {
                 if let Ok(ctxt) = create_context(&self.glx, &extra_functions, &extensions, (3, 2),
-                                                 self.builder.gl_profile, self.builder.gl_debug,
-                                                 self.builder.gl_robustness, share,
+                                                 self.opengl.profile, self.opengl.debug,
+                                                 self.opengl.robustness, share,
                                                  self.display, self.fb_config, &self.visual_infos)
                 {
                     ctxt
                 } else if let Ok(ctxt) = create_context(&self.glx, &extra_functions, &extensions,
-                                                        (3, 1), self.builder.gl_profile,
-                                                        self.builder.gl_debug,
-                                                        self.builder.gl_robustness, share, self.display,
+                                                        (3, 1), self.opengl.profile,
+                                                        self.opengl.debug,
+                                                        self.opengl.robustness, share, self.display,
                                                         self.fb_config, &self.visual_infos)
                 {
                     ctxt
 
                 } else {
                     try!(create_context(&self.glx, &extra_functions, &extensions, (1, 0),
-                                        self.builder.gl_profile, self.builder.gl_debug,
-                                        self.builder.gl_robustness,
+                                        self.opengl.profile, self.opengl.debug,
+                                        self.opengl.robustness,
                                         share, self.display, self.fb_config, &self.visual_infos))
                 }
             },
             GlRequest::Specific(Api::OpenGl, (major, minor)) => {
                 try!(create_context(&self.glx, &extra_functions, &extensions, (major, minor),
-                                    self.builder.gl_profile, self.builder.gl_debug,
-                                    self.builder.gl_robustness, share, self.display, self.fb_config,
+                                    self.opengl.profile, self.opengl.debug,
+                                    self.opengl.robustness, share, self.display, self.fb_config,
                                     &self.visual_infos))
             },
             GlRequest::Specific(_, _) => panic!("Only OpenGL is supported"),
             GlRequest::GlThenGles { opengl_version: (major, minor), .. } => {
                 try!(create_context(&self.glx, &extra_functions, &extensions, (major, minor),
-                                    self.builder.gl_profile, self.builder.gl_debug,
-                                    self.builder.gl_robustness, share, self.display, self.fb_config,
+                                    self.opengl.profile, self.opengl.debug,
+                                    self.opengl.robustness, share, self.display, self.fb_config,
                                     &self.visual_infos))
             },
         };
 
         // vsync
-        if self.builder.vsync {
+        if self.opengl.vsync {
             unsafe { self.glx.MakeCurrent(self.display as *mut _, window, context) };
 
             if extra_functions.SwapIntervalEXT.is_loaded() {
@@ -209,7 +203,8 @@ impl<'a> ContextPrototype<'a> {
                 }
 
                 // checking that it worked
-                if self.builder.strict {
+                // TODO: handle this
+                /*if self.builder.strict {
                     let mut swap = unsafe { mem::uninitialized() };
                     unsafe {
                         self.glx.QueryDrawable(self.display as *mut _, window,
@@ -221,7 +216,7 @@ impl<'a> ContextPrototype<'a> {
                         return Err(CreationError::OsError(format!("Couldn't setup vsync: expected \
                                                     interval `1` but got `{}`", swap)));
                     }
-                }
+                }*/
 
             // GLX_MESA_swap_control is not official
             /*} else if extra_functions.SwapIntervalMESA.is_loaded() {
@@ -234,9 +229,10 @@ impl<'a> ContextPrototype<'a> {
                     extra_functions.SwapIntervalSGI(1);
                 }
 
-            } else if self.builder.strict {
+            }/* else if self.builder.strict {
+                // TODO: handle this
                 return Err(CreationError::OsError(format!("Couldn't find any available vsync extension")));
-            }
+            }*/
 
             unsafe { self.glx.MakeCurrent(self.display as *mut _, 0, ptr::null()) };
         }
diff --git a/src/api/ios/mod.rs b/src/api/ios/mod.rs
index 9d1b527..0163f45 100644
--- a/src/api/ios/mod.rs
+++ b/src/api/ios/mod.rs
@@ -219,7 +219,7 @@ impl Window {
 
         let state = &mut *self.delegate_state;
 
-        if builder.multitouch {
+        if builder.window.multitouch {
             let _: () = msg_send![state.view, setMultipleTouchEnabled:YES];
         }
 
diff --git a/src/api/osmesa/mod.rs b/src/api/osmesa/mod.rs
index 9bd24b6..ca34e93 100644
--- a/src/api/osmesa/mod.rs
+++ b/src/api/osmesa/mod.rs
@@ -3,11 +3,12 @@
 extern crate osmesa_sys;
 
 use Api;
-use BuilderAttribs;
 use ContextError;
 use CreationError;
+use GlAttributes;
 use GlContext;
 use PixelFormat;
+use PixelFormatRequirements;
 use Robustness;
 use libc;
 use std::{mem, ptr};
@@ -32,20 +33,23 @@ impl From<CreationError> for OsMesaCreationError {
 }
 
 impl OsMesaContext {
-    pub fn new(builder: BuilderAttribs) -> Result<OsMesaContext, OsMesaCreationError> {
+    pub fn new(dimensions: (u32, u32), pf_reqs: &PixelFormatRequirements,
+               opengl: &GlAttributes<&OsMesaContext>) -> Result<OsMesaContext, OsMesaCreationError>
+    {
         if let Err(_) = osmesa_sys::OsMesa::try_loading() {
             return Err(OsMesaCreationError::NotSupported);
         }
 
-        let dimensions = builder.dimensions.unwrap();
+        if opengl.sharing.is_some() { unimplemented!() }        // TODO: proper error
 
-        match builder.gl_robustness {
+        match opengl.robustness {
             Robustness::RobustNoResetNotification | Robustness::RobustLoseContextOnReset => {
                 return Err(CreationError::RobustnessNotSupported.into());
             },
             _ => ()
         }
 
+        // TODO: use `pf_reqs` for the format
         // TODO: check OpenGL version and return `OpenGlVersionNotSupported` if necessary
 
         Ok(OsMesaContext {
diff --git a/src/api/wayland/mod.rs b/src/api/wayland/mod.rs
index b46e2d1..10d2acb 100644
--- a/src/api/wayland/mod.rs
+++ b/src/api/wayland/mod.rs
@@ -13,14 +13,16 @@ use api::dlopen;
 use api::egl;
 use api::egl::Context as EglContext;
 
-use BuilderAttribs;
 use ContextError;
 use CreationError;
 use Event;
 use PixelFormat;
 use CursorState;
 use MouseCursor;
+use GlAttributes;
 use GlContext;
+use PixelFormatRequirements;
+use WindowAttributes;
 
 use std::collections::VecDeque;
 use std::ops::{Deref, DerefMut};
@@ -241,7 +243,9 @@ impl<'a> Iterator for WaitEventsIterator<'a> {
 }
 
 impl Window {
-    pub fn new(builder: BuilderAttribs) -> Result<Window, CreationError> {
+    pub fn new(window: &WindowAttributes, pf_reqs: &PixelFormatRequirements,
+               opengl: &GlAttributes<&Window>) -> Result<Window, CreationError>
+    {
         use self::wayland::internals::FFI;
 
         let wayland_context = match *WAYLAND_CONTEXT {
@@ -251,7 +255,7 @@ impl Window {
 
         if !is_egl_available() { return Err(CreationError::NotSupported) }
 
-        let (w, h) = builder.dimensions.unwrap_or((800, 600));
+        let (w, h) = window.dimensions.unwrap_or((800, 600));
 
         let surface = EGLSurface::new(
             wayland_context.compositor.create_surface(),
@@ -259,12 +263,12 @@ impl Window {
             h as i32
         );
 
-        let mut shell_window = if let Some(PlatformMonitorID::Wayland(ref monitor)) = builder.monitor {
+        let mut shell_window = if let Some(PlatformMonitorID::Wayland(ref monitor)) = window.monitor {
             let shell_surface = wayland_context.shell.get_shell_surface(surface);
             shell_surface.set_fullscreen(ShellFullscreenMethod::Default, Some(&monitor.output));
             ShellWindow::Plain(shell_surface)
         } else {
-            if builder.decorations {
+            if window.decorations {
                 ShellWindow::Decorated(match DecoratedSurface::new(
                     surface,
                     w as i32,
@@ -291,7 +295,7 @@ impl Window {
             });
             try!(EglContext::new(
                 egl,
-                &builder,
+                pf_reqs, &opengl.clone().map_sharing(|_| unimplemented!()),        // TODO: 
                 egl::NativeDisplay::Wayland(Some(wayland_context.display.ptr() as *const _)))
                 .and_then(|p| p.finish((**shell_window.get_shell()).ptr() as *const _))
             )
diff --git a/src/api/wgl/mod.rs b/src/api/wgl/mod.rs
index 89538f1..c8a1910 100644
--- a/src/api/wgl/mod.rs
+++ b/src/api/wgl/mod.rs
@@ -1,12 +1,13 @@
 #![cfg(any(target_os = "windows"))]
 
-use BuilderAttribs;
 use ContextError;
 use CreationError;
+use GlAttributes;
 use GlContext;
 use GlRequest;
 use GlProfile;
 use PixelFormat;
+use PixelFormatRequirements;
 use Robustness;
 use Api;
 
@@ -74,9 +75,8 @@ impl Context {
     /// # Unsafety
     ///
     /// The `window` must continue to exist as long as the resulting `Context` exists.
-    pub unsafe fn new(builder: &BuilderAttribs<'static>, window: winapi::HWND,
-                      builder_sharelists: Option<winapi::HGLRC>)
-                      -> Result<Context, CreationError>
+    pub unsafe fn new(pf_reqs: &PixelFormatRequirements, opengl: &GlAttributes<winapi::HGLRC>,
+                      window: winapi::HWND) -> Result<Context, CreationError>
     {
         let hdc = user32::GetDC(window);
         if hdc.is_null() {
@@ -118,20 +118,20 @@ impl Context {
                 enumerate_native_pixel_formats(hdc)
             };
 
-            let (id, f) = try!(builder.choose_pixel_format(formats));
+            let (id, f) = try!(pf_reqs.choose_pixel_format(formats));
             try!(set_pixel_format(hdc, id));
             f
         };
 
         // creating the OpenGL context
-        let context = try!(create_context(Some((&extra_functions, builder, &extensions)),
-                                          window, hdc, builder_sharelists));
+        let context = try!(create_context(Some((&extra_functions, pf_reqs, opengl, &extensions)),
+                                          window, hdc));
 
         // loading the opengl32 module
         let gl_library = try!(load_opengl32_dll());
 
         // handling vsync
-        if builder.vsync {
+        if opengl.vsync {
             if extensions.split(' ').find(|&i| i == "WGL_EXT_swap_control").is_some() {
                 let _guard = try!(CurrentContextGuard::make_current(hdc, context.0));
 
@@ -210,17 +210,20 @@ unsafe impl Sync for Context {}
 ///
 /// Otherwise, only the basic API will be used and the chances of `CreationError::NotSupported`
 /// being returned increase.
-unsafe fn create_context(extra: Option<(&gl::wgl_extra::Wgl, &BuilderAttribs<'static>, &str)>,
-                         _: winapi::HWND, hdc: winapi::HDC, share: Option<winapi::HGLRC>)
+unsafe fn create_context(extra: Option<(&gl::wgl_extra::Wgl, &PixelFormatRequirements,
+                                        &GlAttributes<winapi::HGLRC>, &str)>,
+                         _: winapi::HWND, hdc: winapi::HDC)
                          -> Result<ContextWrapper, CreationError>
 {
-    let share = share.unwrap_or(ptr::null_mut());
+    let share;
+
+    if let Some((extra_functions, pf_reqs, opengl, extensions)) = extra {
+        share = opengl.sharing.unwrap_or(ptr::null_mut());
 
-    if let Some((extra_functions, builder, extensions)) = extra {
         if extensions.split(' ').find(|&i| i == "WGL_ARB_create_context").is_some() {
             let mut attributes = Vec::new();
 
-            match builder.gl_version {
+            match opengl.version {
                 GlRequest::Latest => {},
                 GlRequest::Specific(Api::OpenGl, (major, minor)) => {
                     attributes.push(gl::wgl_extra::CONTEXT_MAJOR_VERSION_ARB as libc::c_int);
@@ -252,7 +255,7 @@ unsafe fn create_context(extra: Option<(&gl::wgl_extra::Wgl, &BuilderAttribs<'st
                 },
             }
 
-            if let Some(profile) = builder.gl_profile {
+            if let Some(profile) = opengl.profile {
                 if extensions.split(' ').find(|&i| i == "WGL_ARB_create_context_profile").is_some()
                 {
                     let flag = match profile {
@@ -273,7 +276,7 @@ unsafe fn create_context(extra: Option<(&gl::wgl_extra::Wgl, &BuilderAttribs<'st
 
                 // robustness
                 if extensions.split(' ').find(|&i| i == "WGL_ARB_create_context_robustness").is_some() {
-                    match builder.gl_robustness {
+                    match opengl.robustness {
                         Robustness::RobustNoResetNotification | Robustness::TryRobustNoResetNotification => {
                             attributes.push(gl::wgl_extra::CONTEXT_RESET_NOTIFICATION_STRATEGY_ARB as libc::c_int);
                             attributes.push(gl::wgl_extra::NO_RESET_NOTIFICATION_ARB as libc::c_int);
@@ -288,7 +291,7 @@ unsafe fn create_context(extra: Option<(&gl::wgl_extra::Wgl, &BuilderAttribs<'st
                         Robustness::NoError => (),
                     }
                 } else {
-                    match builder.gl_robustness {
+                    match opengl.robustness {
                         Robustness::RobustNoResetNotification | Robustness::RobustLoseContextOnReset => {
                             return Err(CreationError::RobustnessNotSupported);
                         },
@@ -296,7 +299,7 @@ unsafe fn create_context(extra: Option<(&gl::wgl_extra::Wgl, &BuilderAttribs<'st
                     }
                 }
 
-                if builder.gl_debug {
+                if opengl.debug {
                     flags = flags | gl::wgl_extra::CONTEXT_DEBUG_BIT_ARB as libc::c_int;
                 }
 
@@ -319,7 +322,10 @@ unsafe fn create_context(extra: Option<(&gl::wgl_extra::Wgl, &BuilderAttribs<'st
                 return Ok(ContextWrapper(ctxt as winapi::HGLRC));
             }
         }
-    };
+
+    } else {
+        share = ptr::null_mut();
+    }
 
     let ctxt = gl::wgl::CreateContext(hdc as *const libc::c_void);
     if ctxt.is_null() {
@@ -544,7 +550,7 @@ unsafe fn load_extra_functions(window: winapi::HWND) -> Result<gl::wgl_extra::Wg
     }
 
     // creating the dummy OpenGL context and making it current
-    let dummy_context = try!(create_context(None, dummy_window.0, dummy_window.1, None));
+    let dummy_context = try!(create_context(None, dummy_window.0, dummy_window.1));
     let _current_context = try!(CurrentContextGuard::make_current(dummy_window.1,
                                                                   dummy_context.0));
 
diff --git a/src/api/win32/init.rs b/src/api/win32/init.rs
index c3225b6..7c7eb83 100644
--- a/src/api/win32/init.rs
+++ b/src/api/win32/init.rs
@@ -11,11 +11,13 @@ use super::WindowWrapper;
 use super::Context;
 
 use Api;
-use BuilderAttribs;
 use CreationError;
 use CreationError::OsError;
 use CursorState;
+use GlAttributes;
 use GlRequest;
+use PixelFormatRequirements;
+use WindowAttributes;
 
 use std::ffi::{OsStr};
 use std::os::windows::ffi::OsStrExt;
@@ -31,6 +33,7 @@ use api::egl;
 use api::egl::Context as EglContext;
 use api::egl::ffi::egl::Egl;
 
+#[derive(Clone)]
 pub enum RawContext {
     Egl(egl::ffi::egl::types::EGLContext),
     Wgl(winapi::HGLRC),
@@ -39,15 +42,18 @@ pub enum RawContext {
 unsafe impl Send for RawContext {}
 unsafe impl Sync for RawContext {}
 
-pub fn new_window(builder: BuilderAttribs<'static>, builder_sharelists: Option<RawContext>,
-                  egl: Option<&Egl>)
+pub fn new_window(window: &WindowAttributes, pf_reqs: &PixelFormatRequirements,
+                  opengl: &GlAttributes<RawContext>, egl: Option<&Egl>)
                   -> Result<Window, CreationError>
 {
     let egl = egl.map(|e| e.clone());
+    let window = window.clone();
+    let pf_reqs = pf_reqs.clone();
+    let opengl = opengl.clone();
 
     // initializing variables to be sent to the task
 
-    let title = OsStr::new(&builder.title).encode_wide().chain(Some(0).into_iter())
+    let title = OsStr::new(&window.title).encode_wide().chain(Some(0).into_iter())
                                           .collect::<Vec<_>>();
 
     let (tx, rx) = channel();
@@ -57,7 +63,7 @@ pub fn new_window(builder: BuilderAttribs<'static>, builder_sharelists: Option<R
     thread::spawn(move || {
         unsafe {
             // creating and sending the `Window`
-            match init(title, builder, builder_sharelists, egl) {
+            match init(title, &window, &pf_reqs, &opengl, egl) {
                 Ok(w) => tx.send(Ok(w)).ok(),
                 Err(e) => {
                     tx.send(Err(e)).ok();
@@ -83,29 +89,36 @@ pub fn new_window(builder: BuilderAttribs<'static>, builder_sharelists: Option<R
     rx.recv().unwrap()
 }
 
-unsafe fn init(title: Vec<u16>, builder: BuilderAttribs<'static>,
-               builder_sharelists: Option<RawContext>, egl: Option<Egl>)
+unsafe fn init(title: Vec<u16>, window: &WindowAttributes, pf_reqs: &PixelFormatRequirements,
+               opengl: &GlAttributes<RawContext>, egl: Option<Egl>)
                -> Result<Window, CreationError>
 {
+    let opengl = opengl.clone().map_sharing(|sharelists| {
+        match sharelists {
+            RawContext::Wgl(c) => c,
+            _ => unimplemented!()
+        }
+    });
+
     // registering the window class
     let class_name = register_window_class();
 
     // building a RECT object with coordinates
     let mut rect = winapi::RECT {
-        left: 0, right: builder.dimensions.unwrap_or((1024, 768)).0 as winapi::LONG,
-        top: 0, bottom: builder.dimensions.unwrap_or((1024, 768)).1 as winapi::LONG,
+        left: 0, right: window.dimensions.unwrap_or((1024, 768)).0 as winapi::LONG,
+        top: 0, bottom: window.dimensions.unwrap_or((1024, 768)).1 as winapi::LONG,
     };
 
     // switching to fullscreen if necessary
     // this means adjusting the window's position so that it overlaps the right monitor,
     //  and change the monitor's resolution if necessary
-    if builder.monitor.is_some() {
-        let monitor = builder.monitor.as_ref().unwrap();
+    if window.monitor.is_some() {
+        let monitor = window.monitor.as_ref().unwrap();
         try!(switch_to_fullscreen(&mut rect, monitor));
     }
 
     // computing the style and extended style of the window
-    let (ex_style, style) = if builder.monitor.is_some() || builder.decorations == false {
+    let (ex_style, style) = if window.monitor.is_some() || window.decorations == false {
         (winapi::WS_EX_APPWINDOW, winapi::WS_POPUP | winapi::WS_CLIPSIBLINGS | winapi::WS_CLIPCHILDREN)
     } else {
         (winapi::WS_EX_APPWINDOW | winapi::WS_EX_WINDOWEDGE,
@@ -117,19 +130,19 @@ unsafe fn init(title: Vec<u16>, builder: BuilderAttribs<'static>,
 
     // creating the real window this time, by using the functions in `extra_functions`
     let real_window = {
-        let (width, height) = if builder.monitor.is_some() || builder.dimensions.is_some() {
+        let (width, height) = if window.monitor.is_some() || window.dimensions.is_some() {
             (Some(rect.right - rect.left), Some(rect.bottom - rect.top))
         } else {
             (None, None)
         };
 
-        let (x, y) = if builder.monitor.is_some() {
+        let (x, y) = if window.monitor.is_some() {
             (Some(rect.left), Some(rect.top))
         } else {
             (None, None)
         };
 
-        let style = if !builder.visible || builder.headless {
+        let style = if !window.visible {
             style
         } else {
             style | winapi::WS_VISIBLE
@@ -159,51 +172,33 @@ unsafe fn init(title: Vec<u16>, builder: BuilderAttribs<'static>,
     };
 
     // creating the OpenGL context
-    let context = match builder.gl_version {
+    let context = match opengl.version {
         GlRequest::Specific(Api::OpenGlEs, (_major, _minor)) => {
             if let Some(egl) = egl {
-                if let Ok(c) = EglContext::new(egl, &builder,
+                if let Ok(c) = EglContext::new(egl, &pf_reqs, &opengl.clone().map_sharing(|_| unimplemented!()),
                                                egl::NativeDisplay::Other(Some(ptr::null())))
                                                              .and_then(|p| p.finish(real_window.0))
                 {
                     Context::Egl(c)
 
                 } else {
-                    let builder_sharelists = match builder_sharelists {
-                        None => None,
-                        Some(RawContext::Wgl(c)) => Some(c),
-                        _ => unimplemented!()
-                    };
-
-                    try!(WglContext::new(&builder, real_window.0, builder_sharelists)
+                    try!(WglContext::new(&pf_reqs, &opengl, real_window.0)
                                         .map(Context::Wgl))
                 }
 
             } else {
                 // falling back to WGL, which is always available
-                let builder_sharelists = match builder_sharelists {
-                    None => None,
-                    Some(RawContext::Wgl(c)) => Some(c),
-                    _ => unimplemented!()
-                };
-
-                try!(WglContext::new(&builder, real_window.0, builder_sharelists)
+                try!(WglContext::new(&pf_reqs, &opengl, real_window.0)
                                     .map(Context::Wgl))
             }
         },
         _ => {
-            let builder_sharelists = match builder_sharelists {
-                None => None,
-                Some(RawContext::Wgl(c)) => Some(c),
-                _ => unimplemented!()
-            };
-
-            try!(WglContext::new(&builder, real_window.0, builder_sharelists).map(Context::Wgl))
+            try!(WglContext::new(&pf_reqs, &opengl, real_window.0).map(Context::Wgl))
         }
     };
 
     // making the window transparent
-    if builder.transparent {
+    if window.transparent {
         let bb = winapi::DWM_BLURBEHIND {
             dwFlags: 0x1, // FIXME: DWM_BB_ENABLE;
             fEnable: 1,
@@ -215,7 +210,7 @@ unsafe fn init(title: Vec<u16>, builder: BuilderAttribs<'static>,
     }
 
     // calling SetForegroundWindow if fullscreen
-    if builder.monitor.is_some() {
+    if window.monitor.is_some() {
         user32::SetForegroundWindow(real_window.0);
     }
 
diff --git a/src/api/win32/mod.rs b/src/api/win32/mod.rs
index dea6357..f580950 100644
--- a/src/api/win32/mod.rs
+++ b/src/api/win32/mod.rs
@@ -13,11 +13,13 @@ use libc;
 use ContextError;
 use {CreationError, Event, MouseCursor};
 use CursorState;
+use GlAttributes;
 use GlContext;
 
 use Api;
 use PixelFormat;
-use BuilderAttribs;
+use PixelFormatRequirements;
+use WindowAttributes;
 
 pub use self::monitor::{MonitorID, get_available_monitors, get_primary_monitor};
 
@@ -83,15 +85,18 @@ impl WindowProxy {
 
 impl Window {
     /// See the docs in the crate root file.
-    pub fn new(builder: BuilderAttribs, egl: Option<&Egl>) -> Result<Window, CreationError> {
-        let (builder, sharing) = builder.extract_non_static();
-
-        let sharing = sharing.map(|w| match w.context {
-            Context::Wgl(ref c) => RawContext::Wgl(c.get_hglrc()),
-            Context::Egl(_) => unimplemented!(),        // FIXME: 
+    pub fn new(window: &WindowAttributes, pf_reqs: &PixelFormatRequirements,
+               opengl: &GlAttributes<&Window>, egl: Option<&Egl>)
+               -> Result<Window, CreationError>
+    {
+        let opengl = opengl.clone().map_sharing(|sharing| {
+            match sharing.context {
+                Context::Wgl(ref c) => RawContext::Wgl(c.get_hglrc()),
+                Context::Egl(_) => unimplemented!(),        // FIXME: 
+            }
         });
 
-        init::new_window(builder, sharing, egl)
+        init::new_window(window, pf_reqs, &opengl, egl)
     }
 
     /// See the docs in the crate root file.
diff --git a/src/api/x11/window.rs b/src/api/x11/window.rs
index 5bfbda9..3032bfd 100644
--- a/src/api/x11/window.rs
+++ b/src/api/x11/window.rs
@@ -1,4 +1,4 @@
-use {Event, BuilderAttribs, MouseCursor};
+use {Event, MouseCursor};
 use CreationError;
 use CreationError::OsError;
 use libc;
@@ -12,9 +12,12 @@ use std::sync::{Arc, Mutex};
 use Api;
 use ContextError;
 use CursorState;
+use GlAttributes;
 use GlContext;
 use GlRequest;
 use PixelFormat;
+use PixelFormatRequirements;
+use WindowAttributes;
 
 use api::glx::Context as GlxContext;
 use api::egl;
@@ -295,10 +298,13 @@ pub struct Window {
 }
 
 impl Window {
-    pub fn new(display: &Arc<XConnection>, builder: BuilderAttribs) -> Result<Window, CreationError> {
-        let dimensions = builder.dimensions.unwrap_or((800, 600));
+    pub fn new(display: &Arc<XConnection>, window_attrs: &WindowAttributes,
+               pf_reqs: &PixelFormatRequirements, opengl: &GlAttributes<&Window>)
+               -> Result<Window, CreationError>
+    {
+        let dimensions = window_attrs.dimensions.unwrap_or((800, 600));
 
-        let screen_id = match builder.monitor {
+        let screen_id = match window_attrs.monitor {
             Some(PlatformMonitorID::X(MonitorID(_, monitor))) => monitor as i32,
             _ => unsafe { (display.xlib.XDefaultScreen)(display.display) },
         };
@@ -316,7 +322,7 @@ impl Window {
             // FIXME: `XF86VidModeModeInfo` is missing its `hskew` field. Therefore we point to
             //        `vsyncstart` instead of `vdisplay` as a temporary hack.
 
-            let mode_to_switch_to = if builder.monitor.is_some() {
+            let mode_to_switch_to = if window_attrs.monitor.is_some() {
                 let matching_mode = (0 .. mode_num).map(|i| {
                     let m: ffi::XF86VidModeModeInfo = ptr::read(*modes.offset(i as isize) as *const _); m
                 }).find(|m| m.hdisplay == dimensions.0 as u16 && m.vsyncstart == dimensions.1 as u16);
@@ -348,22 +354,23 @@ impl Window {
             Glx(::api::glx::ContextPrototype<'a>),
             Egl(::api::egl::ContextPrototype<'a>),
         }
-        let builder_clone = builder.clone();
-        let context = match builder.gl_version {
+        let builder_clone_opengl_glx = opengl.clone().map_sharing(|_| unimplemented!());      // FIXME: 
+        let builder_clone_opengl_egl = opengl.clone().map_sharing(|_| unimplemented!());      // FIXME: 
+        let context = match opengl.version {
             GlRequest::Latest | GlRequest::Specific(Api::OpenGl, _) | GlRequest::GlThenGles { .. } => {
                 // GLX should be preferred over EGL, otherwise crashes may occur
                 // on X11 – issue #314
                 if let Some(ref glx) = display.glx {
-                    Prototype::Glx(try!(GlxContext::new(glx.clone(), &display.xlib, &builder_clone, display.display)))
+                    Prototype::Glx(try!(GlxContext::new(glx.clone(), &display.xlib, pf_reqs, &builder_clone_opengl_glx, display.display)))
                 } else if let Some(ref egl) = display.egl {
-                    Prototype::Egl(try!(EglContext::new(egl.clone(), &builder_clone, egl::NativeDisplay::X11(Some(display.display as *const _)))))
+                    Prototype::Egl(try!(EglContext::new(egl.clone(), pf_reqs, &builder_clone_opengl_egl, egl::NativeDisplay::X11(Some(display.display as *const _)))))
                 } else {
                     return Err(CreationError::NotSupported);
                 }
             },
             GlRequest::Specific(Api::OpenGlEs, _) => {
                 if let Some(ref egl) = display.egl {
-                    Prototype::Egl(try!(EglContext::new(egl.clone(), &builder_clone, egl::NativeDisplay::X11(Some(display.display as *const _)))))
+                    Prototype::Egl(try!(EglContext::new(egl.clone(), pf_reqs, &builder_clone_opengl_egl, egl::NativeDisplay::X11(Some(display.display as *const _)))))
                 } else {
                     return Err(CreationError::NotSupported);
                 }
@@ -415,7 +422,7 @@ impl Window {
                 ffi::KeyReleaseMask | ffi::ButtonPressMask |
                 ffi::ButtonReleaseMask | ffi::KeymapStateMask;
             swa.border_pixel = 0;
-            if builder.transparent {
+            if window_attrs.transparent {
                 swa.background_pixel = 0;
             }
             swa.override_redirect = 0;
@@ -424,7 +431,7 @@ impl Window {
 
         let mut window_attributes = ffi::CWBorderPixel | ffi::CWColormap | ffi::CWEventMask;
 
-        if builder.transparent {
+        if window_attrs.transparent {
             window_attributes |= ffi::CWBackPixel;
         }
 
@@ -448,7 +455,7 @@ impl Window {
         };
 
         // set visibility
-        if builder.visible {
+        if window_attrs.visible {
             unsafe {
                 (display.xlib.XMapRaised)(display.display, window);
                 (display.xlib.XFlush)(display.display);
@@ -461,7 +468,7 @@ impl Window {
                 (display.xlib.XInternAtom)(display.display, delete_window, 0)
             );
             (display.xlib.XSetWMProtocols)(display.display, window, &mut wm_delete_window, 1);
-            with_c_str(&*builder.title, |title| {;
+            with_c_str(&*window_attrs.title, |title| {;
                 (display.xlib.XStoreName)(display.display, window, title);
             });
             (display.xlib.XFlush)(display.display);
@@ -509,7 +516,7 @@ impl Window {
 
         // Set ICCCM WM_CLASS property based on initial window title
         unsafe {
-            with_c_str(&*builder.title, |c_name| {
+            with_c_str(&*window_attrs.title, |c_name| {
                 let hint = (display.xlib.XAllocClassHint)();
                 (*hint).res_name = c_name as *mut libc::c_char;
                 (*hint).res_class = c_name as *mut libc::c_char;
@@ -518,7 +525,7 @@ impl Window {
             });
         }
 
-        let is_fullscreen = builder.monitor.is_some();
+        let is_fullscreen = window_attrs.monitor.is_some();
 
         // finish creating the OpenGL context
         let context = match context {
diff --git a/src/headless.rs b/src/headless.rs
index 69f9aab..4730eb4 100644
--- a/src/headless.rs
+++ b/src/headless.rs
@@ -1,11 +1,13 @@
 use Api;
-use BuilderAttribs;
 use ContextError;
 use CreationError;
+use GlAttributes;
 use GlRequest;
 use GlContext;
 use PixelFormat;
+use PixelFormatRequirements;
 use Robustness;
+use WindowAttributes;
 
 use gl_common;
 use libc;
@@ -13,25 +15,25 @@ use libc;
 use platform;
 
 /// Object that allows you to build headless contexts.
-pub struct HeadlessRendererBuilder {
-    attribs: BuilderAttribs<'static>,
+pub struct HeadlessRendererBuilder<'a> {
+    dimensions: (u32, u32),
+    pf_reqs: PixelFormatRequirements,
+    opengl: GlAttributes<&'a platform::HeadlessContext>,
 }
 
-impl HeadlessRendererBuilder {
+impl<'a> HeadlessRendererBuilder<'a> {
     /// Initializes a new `HeadlessRendererBuilder` with default values.
-    pub fn new(width: u32, height: u32) -> HeadlessRendererBuilder {
+    pub fn new(width: u32, height: u32) -> HeadlessRendererBuilder<'a> {
         HeadlessRendererBuilder {
-            attribs: BuilderAttribs {
-                headless: true,
-                dimensions: Some((width, height)),
-                .. BuilderAttribs::new()
-            },
+            dimensions: (width, height),
+            pf_reqs: Default::default(),
+            opengl: Default::default(),
         }
     }
 
     /// Sets how the backend should choose the OpenGL API and version.
-    pub fn with_gl(mut self, request: GlRequest) -> HeadlessRendererBuilder {
-        self.attribs.gl_version = request;
+    pub fn with_gl(mut self, request: GlRequest) -> HeadlessRendererBuilder<'a> {
+        self.opengl.version = request;
         self
     }
 
@@ -39,14 +41,14 @@ impl HeadlessRendererBuilder {
     ///
     /// The default value for this flag is `cfg!(ndebug)`, which means that it's enabled
     /// when you run `cargo build` and disabled when you run `cargo build --release`.
-    pub fn with_gl_debug_flag(mut self, flag: bool) -> HeadlessRendererBuilder {
-        self.attribs.gl_debug = flag;
+    pub fn with_gl_debug_flag(mut self, flag: bool) -> HeadlessRendererBuilder<'a> {
+        self.opengl.debug = flag;
         self
     }
 
     /// Sets the robustness of the OpenGL context. See the docs of `Robustness`.
-    pub fn with_gl_robustness(mut self, robustness: Robustness) -> HeadlessRendererBuilder {
-        self.attribs.gl_robustness = robustness;
+    pub fn with_gl_robustness(mut self, robustness: Robustness) -> HeadlessRendererBuilder<'a> {
+        self.opengl.robustness = robustness;
         self
     }
 
@@ -55,15 +57,15 @@ impl HeadlessRendererBuilder {
     /// Error should be very rare and only occur in case of permission denied, incompatible system,
     ///  out of memory, etc.
     pub fn build(self) -> Result<HeadlessContext, CreationError> {
-        platform::HeadlessContext::new(self.attribs).map(|w| HeadlessContext { context: w })
+        platform::HeadlessContext::new(self.dimensions, &self.pf_reqs, &self.opengl)
+                .map(|w| HeadlessContext { context: w })
     }
 
     /// Builds the headless context.
     ///
     /// The context is build in a *strict* way. That means that if the backend couldn't give
     /// you what you requested, an `Err` will be returned.
-    pub fn build_strict(mut self) -> Result<HeadlessContext, CreationError> {
-        self.attribs.strict = true;
+    pub fn build_strict(self) -> Result<HeadlessContext, CreationError> {
         self.build()
     }
 }
diff --git a/src/lib.rs b/src/lib.rs
index 24913fb..a75a47a 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -362,99 +362,21 @@ pub struct PixelFormat {
     pub multisampling: Option<u16>,
     pub srgb: bool,
 }
-
-/// Attributes
-// FIXME: remove `pub` (https://github.com/rust-lang/rust/issues/23585)
-#[derive(Clone)]
-#[doc(hidden)]
-pub struct BuilderAttribs<'a> {
-    #[allow(dead_code)]
-    headless: bool,
-    strict: bool,
-    sharing: Option<&'a platform::Window>,
-    dimensions: Option<(u32, u32)>,
-    title: String,
-    monitor: Option<platform::MonitorID>,
-    gl_version: GlRequest,
-    gl_profile: Option<GlProfile>,
-    gl_debug: bool,
-    gl_robustness: Robustness,
-    vsync: bool,
-    visible: bool,
-    multisampling: Option<u16>,
-    depth_bits: Option<u8>,
-    stencil_bits: Option<u8>,
-    color_bits: Option<u8>,
-    alpha_bits: Option<u8>,
-    stereoscopy: bool,
-    srgb: Option<bool>,
-    transparent: bool,
-    decorations: bool,
-    multitouch: bool
-}
-
-impl BuilderAttribs<'static> {
-    fn new() -> BuilderAttribs<'static> {
-        BuilderAttribs {
-            headless: false,
-            strict: false,
-            sharing: None,
-            dimensions: None,
-            title: "glutin window".to_string(),
-            monitor: None,
-            gl_version: GlRequest::Latest,
-            gl_profile: None,
-            gl_debug: cfg!(debug_assertions),
-            gl_robustness: Robustness::NotRobust,
-            vsync: false,
-            visible: true,
-            multisampling: None,
-            depth_bits: None,
-            stencil_bits: None,
-            color_bits: None,
-            alpha_bits: None,
-            stereoscopy: false,
-            srgb: None,
-            transparent: false,
-            decorations: true,
-            multitouch: false
-        }
-    }
+    
+/// VERY UNSTABLE! Describes how the backend should choose a pixel format.
+#[derive(Clone, Debug)]
+#[allow(missing_docs)]
+pub struct PixelFormatRequirements {
+    pub multisampling: Option<u16>,
+    pub depth_bits: Option<u8>,
+    pub stencil_bits: Option<u8>,
+    pub color_bits: Option<u8>,
+    pub alpha_bits: Option<u8>,
+    pub stereoscopy: bool,
+    pub srgb: Option<bool>,
 }
 
-impl<'a> BuilderAttribs<'a> {
-    #[allow(dead_code)]
-    fn extract_non_static(mut self) -> (BuilderAttribs<'static>, Option<&'a platform::Window>) {
-        let sharing = self.sharing.take();
-
-        let new_attribs = BuilderAttribs {
-            headless: self.headless,
-            strict: self.strict,
-            sharing: None,
-            dimensions: self.dimensions,
-            title: self.title,
-            monitor: self.monitor,
-            gl_version: self.gl_version,
-            gl_profile: self.gl_profile,
-            gl_debug: self.gl_debug,
-            gl_robustness: self.gl_robustness,
-            vsync: self.vsync,
-            visible: self.visible,
-            multisampling: self.multisampling,
-            depth_bits: self.depth_bits,
-            stencil_bits: self.stencil_bits,
-            color_bits: self.color_bits,
-            alpha_bits: self.alpha_bits,
-            stereoscopy: self.stereoscopy,
-            srgb: self.srgb,
-            transparent: self.transparent,
-            decorations: self.decorations,
-            multitouch: self.multitouch
-        };
-
-        (new_attribs, sharing)
-    }
-
+impl PixelFormatRequirements {
     fn choose_pixel_format<T, I>(&self, iter: I) -> Result<(T, PixelFormat), CreationError>
                                  where I: IntoIterator<Item=(T, PixelFormat)>, T: Clone
     {
@@ -555,6 +477,138 @@ impl<'a> BuilderAttribs<'a> {
     }
 }
 
+impl Default for PixelFormatRequirements {
+    fn default() -> PixelFormatRequirements {
+        PixelFormatRequirements {
+            multisampling: None,
+            depth_bits: None,
+            stencil_bits: None,
+            color_bits: None,
+            alpha_bits: None,
+            stereoscopy: false,
+            srgb: None,
+        }
+    }
+}
+
+/// Attributes to use when creating a window.
+#[derive(Clone)]
+pub struct WindowAttributes {
+    /// The dimensions of the window. If this is `None`, some platform-specific dimensions will be
+    /// used.
+    ///
+    /// The default is `None`.
+    pub dimensions: Option<(u32, u32)>,
+
+    /// If `Some`, the window will be in fullscreen mode with the given monitor.
+    ///
+    /// The default is `None`.
+    pub monitor: Option<platform::MonitorID>,
+
+    /// The title of the window in the title bar.
+    ///
+    /// The default is `"glutin window"`.
+    pub title: String,
+
+    /// Whether the window should be immediately visible upon creation.
+    ///
+    /// The default is `true`.
+    pub visible: bool,
+
+    /// Whether the the window should be transparent. If this is true, writing colors
+    /// with alpha values different than `1.0` will produce a transparent window.
+    ///
+    /// The default is `false`.
+    pub transparent: bool,
+
+    /// Whether the window should have borders and bars.
+    ///
+    /// The default is `true`.
+    pub decorations: bool,
+
+    /// ??? TODO: document me
+    pub multitouch: bool,
+}
+
+impl Default for WindowAttributes {
+    fn default() -> WindowAttributes {
+        WindowAttributes {
+            dimensions: None,
+            monitor: None,
+            title: "glutin window".to_owned(),
+            visible: true,
+            transparent: false,
+            decorations: true,
+            multitouch: false,
+        }
+    }
+}
+
+/// Attributes to use when creating an OpenGL context.
+#[derive(Clone)]
+pub struct GlAttributes<S> {
+    /// An existing context to share the new the context with.
+    ///
+    /// The default is `None`.
+    pub sharing: Option<S>,
+
+    /// Version to try create. See `GlRequest` for more infos.
+    ///
+    /// The default is `Latest`.
+    pub version: GlRequest,
+
+    /// OpenGL profile to use.
+    ///
+    /// The default is `None`.
+    pub profile: Option<GlProfile>,
+
+    /// Whether to enable the `debug` flag of the context.
+    ///
+    /// Debug contexts are usually slower but give better error reporting.
+    ///
+    /// The default is `true` in debug mode and `false` in release mode.
+    pub debug: bool,
+
+    /// How the OpenGL context should detect errors.
+    ///
+    /// The default is `NotRobust` because this is what is typically expected when you create an
+    /// OpenGL context. However for safety you should consider `TryRobustLoseContextOnReset`.
+    pub robustness: Robustness,
+
+    /// Whether to use vsync. If vsync is enabled, calling `swap_buffers` will block until the
+    /// screen refreshes. This is typically used to prevent screen tearing.
+    ///
+    /// The default is `false`.
+    pub vsync: bool,
+}
+
+impl<S> GlAttributes<S> {
+    /// Turns the `sharing` parameter into another type by calling a closure.
+    pub fn map_sharing<F, T>(self, f: F) -> GlAttributes<T> where F: FnOnce(S) -> T {
+        GlAttributes {
+            sharing: self.sharing.map(f),
+            version: self.version,
+            profile: self.profile,
+            debug: self.debug,
+            robustness: self.robustness,
+            vsync: self.vsync,
+        }
+    }
+}
+
+impl<S> Default for GlAttributes<S> {
+    fn default() -> GlAttributes<S> {
+        GlAttributes {
+            sharing: None,
+            version: GlRequest::Latest,
+            profile: None,
+            debug: cfg!(debug_assertions),
+            robustness: Robustness::NotRobust,
+            vsync: false,
+        }
+    }
+}
+
 mod native_monitor {
     /// Native platform identifier for a monitor. Different platforms use fundamentally different types
     /// to represent a monitor ID.
diff --git a/src/platform/linux/api_dispatch.rs b/src/platform/linux/api_dispatch.rs
index f25bda9..46c58bb 100644
--- a/src/platform/linux/api_dispatch.rs
+++ b/src/platform/linux/api_dispatch.rs
@@ -6,14 +6,16 @@ pub use api::x11::{WaitEventsIterator, PollEventsIterator};*/
 use std::collections::VecDeque;
 use std::sync::Arc;
 
-use BuilderAttribs;
 use ContextError;
 use CreationError;
 use CursorState;
 use Event;
+use GlAttributes;
 use GlContext;
 use MouseCursor;
 use PixelFormat;
+use PixelFormatRequirements;
+use WindowAttributes;
 use libc;
 
 use api::wayland;
@@ -161,10 +163,28 @@ impl<'a> Iterator for WaitEventsIterator<'a> {
 }
 
 impl Window {
-    pub fn new(builder: BuilderAttribs) -> Result<Window, CreationError> {
+    pub fn new(window: &WindowAttributes, pf_reqs: &PixelFormatRequirements,
+               opengl: &GlAttributes<&Window>) -> Result<Window, CreationError>
+    {
         match *BACKEND {
-            Backend::Wayland => wayland::Window::new(builder).map(Window::Wayland),
-            Backend::X(ref connec) => x11::Window::new(connec, builder).map(Window::X),
+            Backend::Wayland => {
+                let opengl = opengl.clone().map_sharing(|w| match w {
+                    &Window::Wayland(ref w) => w,
+                    _ => panic!()       // TODO: return an error
+                });
+
+                wayland::Window::new(window, pf_reqs, &opengl).map(Window::Wayland)
+            },
+
+            Backend::X(ref connec) => {
+                let opengl = opengl.clone().map_sharing(|w| match w {
+                    &Window::X(ref w) => w,
+                    _ => panic!()       // TODO: return an error
+                });
+
+                x11::Window::new(connec, window, pf_reqs, &opengl).map(Window::X)
+            },
+
             Backend::Error(ref error) => Err(CreationError::NoBackendAvailable(Box::new(error.clone())))
         }
     }
diff --git a/src/platform/linux/mod.rs b/src/platform/linux/mod.rs
index 3525ce5..f5d663b 100644
--- a/src/platform/linux/mod.rs
+++ b/src/platform/linux/mod.rs
@@ -1,11 +1,12 @@
 #![cfg(any(target_os = "linux", target_os = "dragonfly", target_os = "freebsd"))]
 
 use Api;
-use BuilderAttribs;
 use ContextError;
 use CreationError;
+use GlAttributes;
 use GlContext;
 use PixelFormat;
+use PixelFormatRequirements;
 use libc;
 
 use api::osmesa::{self, OsMesaContext};
@@ -25,8 +26,12 @@ pub type MonitorID = ();       // TODO: hack to make things work
 pub struct HeadlessContext(OsMesaContext);
 
 impl HeadlessContext {
-    pub fn new(builder: BuilderAttribs) -> Result<HeadlessContext, CreationError> {
-        match OsMesaContext::new(builder) {
+    pub fn new(dimensions: (u32, u32), pf_reqs: &PixelFormatRequirements,
+               opengl: &GlAttributes<&HeadlessContext>) -> Result<HeadlessContext, CreationError>
+    {
+        let opengl = opengl.clone().map_sharing(|c| &c.0);
+
+        match OsMesaContext::new(dimensions, pf_reqs, &opengl) {
             Ok(c) => return Ok(HeadlessContext(c)),
             Err(osmesa::OsMesaCreationError::NotSupported) => (),
             Err(osmesa::OsMesaCreationError::CreationError(e)) => return Err(e),
diff --git a/src/platform/windows/mod.rs b/src/platform/windows/mod.rs
index 7087a23..af9261f 100644
--- a/src/platform/windows/mod.rs
+++ b/src/platform/windows/mod.rs
@@ -7,11 +7,13 @@ pub use api::win32::{WindowProxy, PollEventsIterator, WaitEventsIterator};
 use libc;
 
 use Api;
-use BuilderAttribs;
 use ContextError;
 use CreationError;
 use PixelFormat;
+use PixelFormatRequirements;
+use GlAttributes;
 use GlContext;
+use WindowAttributes;
 
 use api::egl::ffi::egl::Egl;
 use api::egl;
@@ -57,8 +59,11 @@ pub struct Window(win32::Window);
 
 impl Window {
     /// See the docs in the crate root file.
-    pub fn new(builder: BuilderAttribs) -> Result<Window, CreationError> {
-        win32::Window::new(builder, EGL.as_ref().map(|w| &w.0)).map(|w| Window(w))
+    pub fn new(window: &WindowAttributes, pf_reqs: &PixelFormatRequirements,
+               opengl: &GlAttributes<&Window>) -> Result<Window, CreationError>
+    {
+        win32::Window::new(window, pf_reqs, &opengl.clone().map_sharing(|w| &w.0),
+                           EGL.as_ref().map(|w| &w.0)).map(|w| Window(w))
     }
 }
 
@@ -85,14 +90,15 @@ pub enum HeadlessContext {
 }
 
 impl HeadlessContext {
-    pub fn new(mut builder: BuilderAttribs) -> Result<HeadlessContext, CreationError> {
-        builder.visible = false;
-
+    pub fn new(dimensions: (u32, u32), pf_reqs: &PixelFormatRequirements,
+               opengl: &GlAttributes<&HeadlessContext>) -> Result<HeadlessContext, CreationError>
+    {
         // if EGL is available, we try using EGL first
         // if EGL returns an error, we try the hidden window method
         if let &Some(ref egl) = &*EGL {
-            let context = EglContext::new(egl.0.clone(), &builder, egl::NativeDisplay::Other(None))
-                                .and_then(|prototype| prototype.finish_pbuffer())
+            let context = EglContext::new(egl.0.clone(), pf_reqs, &opengl.clone().map_sharing(|_| unimplemented!()),       // TODO: 
+                                          egl::NativeDisplay::Other(None))
+                                .and_then(|prototype| prototype.finish_pbuffer(dimensions))
                                 .map(|ctxt| HeadlessContext::EglPbuffer(ctxt));
 
             if let Ok(context) = context {
@@ -100,7 +106,9 @@ impl HeadlessContext {
             }
         }
 
-        let window = try!(win32::Window::new(builder, EGL.as_ref().map(|w| &w.0)));
+        let window = try!(win32::Window::new(&WindowAttributes { visible: false, .. Default::default() },
+                                             pf_reqs, &opengl.clone().map_sharing(|_| unimplemented!()),            //TODO:
+                                             EGL.as_ref().map(|w| &w.0)));
         Ok(HeadlessContext::HiddenWindow(window))
     }
 }
diff --git a/src/window.rs b/src/window.rs
index 00174d3..246f5c9 100644
--- a/src/window.rs
+++ b/src/window.rs
@@ -2,17 +2,19 @@ use std::collections::vec_deque::IntoIter as VecDequeIter;
 use std::default::Default;
 
 use Api;
-use BuilderAttribs;
 use ContextError;
 use CreationError;
 use CursorState;
 use Event;
+use GlAttributes;
 use GlContext;
 use GlProfile;
 use GlRequest;
 use MouseCursor;
 use PixelFormat;
+use PixelFormatRequirements;
 use Robustness;
+use WindowAttributes;
 use native_monitor::NativeMonitorId;
 
 use gl_common;
@@ -22,14 +24,18 @@ use platform;
 
 /// Object that allows you to build windows.
 pub struct WindowBuilder<'a> {
-    attribs: BuilderAttribs<'a>
+    pf_reqs: PixelFormatRequirements,
+    window: WindowAttributes,
+    opengl: GlAttributes<&'a platform::Window>,
 }
 
 impl<'a> WindowBuilder<'a> {
     /// Initializes a new `WindowBuilder` with default values.
     pub fn new() -> WindowBuilder<'a> {
         WindowBuilder {
-            attribs: BuilderAttribs::new(),
+            pf_reqs: Default::default(),
+            window: Default::default(),
+            opengl: Default::default(),
         }
     }
 
@@ -37,13 +43,13 @@ impl<'a> WindowBuilder<'a> {
     ///
     /// Width and height are in pixels.
     pub fn with_dimensions(mut self, width: u32, height: u32) -> WindowBuilder<'a> {
-        self.attribs.dimensions = Some((width, height));
+        self.window.dimensions = Some((width, height));
         self
     }
 
     /// Requests a specific title for the window.
     pub fn with_title(mut self, title: String) -> WindowBuilder<'a> {
-        self.attribs.title = title;
+        self.window.title = title;
         self
     }
 
@@ -52,7 +58,7 @@ impl<'a> WindowBuilder<'a> {
     /// If you don't specify dimensions for the window, it will match the monitor's.
     pub fn with_fullscreen(mut self, monitor: MonitorID) -> WindowBuilder<'a> {
         let MonitorID(monitor) = monitor;
-        self.attribs.monitor = Some(monitor);
+        self.window.monitor = Some(monitor);
         self
     }
 
@@ -60,19 +66,19 @@ impl<'a> WindowBuilder<'a> {
     ///
     /// There are some exceptions, like FBOs or VAOs. See the OpenGL documentation.
     pub fn with_shared_lists(mut self, other: &'a Window) -> WindowBuilder<'a> {
-        self.attribs.sharing = Some(&other.window);
+        self.opengl.sharing = Some(&other.window);
         self
     }
 
     /// Sets how the backend should choose the OpenGL API and version.
     pub fn with_gl(mut self, request: GlRequest) -> WindowBuilder<'a> {
-        self.attribs.gl_version = request;
+        self.opengl.version = request;
         self
     }
 
     /// Sets the desired OpenGL context profile.
     pub fn with_gl_profile(mut self, profile: GlProfile) -> WindowBuilder<'a> {
-        self.attribs.gl_profile = Some(profile);
+        self.opengl.profile = Some(profile);
         self
     }
 
@@ -81,25 +87,25 @@ impl<'a> WindowBuilder<'a> {
     /// The default value for this flag is `cfg!(debug_assertions)`, which means that it's enabled
     /// when you run `cargo build` and disabled when you run `cargo build --release`.
     pub fn with_gl_debug_flag(mut self, flag: bool) -> WindowBuilder<'a> {
-        self.attribs.gl_debug = flag;
+        self.opengl.debug = flag;
         self
     }
 
     /// Sets the robustness of the OpenGL context. See the docs of `Robustness`.
     pub fn with_gl_robustness(mut self, robustness: Robustness) -> WindowBuilder<'a> {
-        self.attribs.gl_robustness = robustness;
+        self.opengl.robustness = robustness;
         self
     }
 
     /// Requests that the window has vsync enabled.
     pub fn with_vsync(mut self) -> WindowBuilder<'a> {
-        self.attribs.vsync = true;
+        self.opengl.vsync = true;
         self
     }
 
     /// Sets whether the window will be initially hidden or visible.
     pub fn with_visibility(mut self, visible: bool) -> WindowBuilder<'a> {
-        self.attribs.visible = visible;
+        self.window.visible = visible;
         self
     }
 
@@ -110,56 +116,56 @@ impl<'a> WindowBuilder<'a> {
     /// Will panic if `samples` is not a power of two.
     pub fn with_multisampling(mut self, samples: u16) -> WindowBuilder<'a> {
         assert!(samples.is_power_of_two());
-        self.attribs.multisampling = Some(samples);
+        self.pf_reqs.multisampling = Some(samples);
         self
     }
 
     /// Sets the number of bits in the depth buffer.
     pub fn with_depth_buffer(mut self, bits: u8) -> WindowBuilder<'a> {
-        self.attribs.depth_bits = Some(bits);
+        self.pf_reqs.depth_bits = Some(bits);
         self
     }
 
     /// Sets the number of bits in the stencil buffer.
     pub fn with_stencil_buffer(mut self, bits: u8) -> WindowBuilder<'a> {
-        self.attribs.stencil_bits = Some(bits);
+        self.pf_reqs.stencil_bits = Some(bits);
         self
     }
 
     /// Sets the number of bits in the color buffer.
     pub fn with_pixel_format(mut self, color_bits: u8, alpha_bits: u8) -> WindowBuilder<'a> {
-        self.attribs.color_bits = Some(color_bits);
-        self.attribs.alpha_bits = Some(alpha_bits);
+        self.pf_reqs.color_bits = Some(color_bits);
+        self.pf_reqs.alpha_bits = Some(alpha_bits);
         self
     }
 
     /// Request the backend to be stereoscopic.
     pub fn with_stereoscopy(mut self) -> WindowBuilder<'a> {
-        self.attribs.stereoscopy = true;
+        self.pf_reqs.stereoscopy = true;
         self
     }
 
     /// Sets whether sRGB should be enabled on the window. `None` means "I don't care".
     pub fn with_srgb(mut self, srgb_enabled: Option<bool>) -> WindowBuilder<'a> {
-        self.attribs.srgb = srgb_enabled;
+        self.pf_reqs.srgb = srgb_enabled;
         self
     }
 
     /// Sets whether the background of the window should be transparent.
     pub fn with_transparency(mut self, transparent: bool) -> WindowBuilder<'a> {
-        self.attribs.transparent = transparent;
+        self.window.transparent = transparent;
         self
     }
 
     /// Sets whether the window should have a border, a title bar, etc.
     pub fn with_decorations(mut self, decorations: bool) -> WindowBuilder<'a> {
-        self.attribs.decorations = decorations;
+        self.window.decorations = decorations;
         self
     }
 
     /// Enables multitouch
     pub fn with_multitouch(mut self) -> WindowBuilder<'a> {
-        self.attribs.multitouch = true;
+        self.window.multitouch = true;
         self
     }
 
@@ -169,25 +175,25 @@ impl<'a> WindowBuilder<'a> {
     /// out of memory, etc.
     pub fn build(mut self) -> Result<Window, CreationError> {
         // resizing the window to the dimensions of the monitor when fullscreen
-        if self.attribs.dimensions.is_none() && self.attribs.monitor.is_some() {
-            self.attribs.dimensions = Some(self.attribs.monitor.as_ref().unwrap().get_dimensions())
+        if self.window.dimensions.is_none() && self.window.monitor.is_some() {
+            self.window.dimensions = Some(self.window.monitor.as_ref().unwrap().get_dimensions())
         }
 
         // default dimensions
-        if self.attribs.dimensions.is_none() {
-            self.attribs.dimensions = Some((1024, 768));
+        if self.window.dimensions.is_none() {
+            self.window.dimensions = Some((1024, 768));
         }
 
         // building
-        platform::Window::new(self.attribs).map(|w| Window { window: w })
+        platform::Window::new(&self.window, &self.pf_reqs, &self.opengl)
+                            .map(|w| Window { window: w })
     }
 
     /// Builds the window.
     ///
     /// The context is build in a *strict* way. That means that if the backend couldn't give
     /// you what you requested, an `Err` will be returned.
-    pub fn build_strict(mut self) -> Result<Window, CreationError> {
-        self.attribs.strict = true;
+    pub fn build_strict(self) -> Result<Window, CreationError> {
         self.build()
     }
 }