Ensured windows start and remain 4:3, made sure I request a GL 3.2 context and that an exception is raised if I call any old-fashioned GL functions.

OSBindings/Mac/Clock Signal/Atari2600Document.swift

@@ -20,6 +20,8 @@ class Atari2600Document: NSDocument, CSOpenGLViewDelegate, CSAtari2600Delegate {
 		super.windowControllerDidLoadNib(aController)
 
 		openGLView!.delegate = self
+
+		// bind the content aspect ratio to remain 4:3 from now on
 		aController.window!.contentAspectRatio = NSSize(width: 4.0, height: 3.0)
 	}
 
@@ -41,9 +43,6 @@ class Atari2600Document: NSDocument, CSOpenGLViewDelegate, CSAtari2600Delegate {
 	}
 
 	override func readFromData(data: NSData, ofType typeName: String) throws {
-		// Insert code here to read your document from the given data of the specified type. If outError != nil, ensure that you create and set an appropriate error when returning false.
-		// You can also choose to override readFromFileWrapper:ofType:error: or readFromURL:ofType:error: instead.
-		// If you override either of these, you should also override -isEntireFileLoaded to return false if the contents are lazily loaded.
 		atari2600 = CSAtari2600()
 		atari2600!.setROM(data)
 		atari2600!.delegate = self

OSBindings/Mac/Clock Signal/Base.lproj/Atari2600Document.xib

@@ -16,15 +16,14 @@
             <windowStyleMask key="styleMask" titled="YES" closable="YES" miniaturizable="YES" resizable="YES"/>
             <windowCollectionBehavior key="collectionBehavior" fullScreenPrimary="YES"/>
             <windowPositionMask key="initialPositionMask" leftStrut="YES" rightStrut="YES" topStrut="YES" bottomStrut="YES"/>
-            <rect key="contentRect" x="133" y="235" width="507" height="413"/>
+            <rect key="contentRect" x="133" y="235" width="400" height="300"/>
             <rect key="screenRect" x="0.0" y="0.0" width="2560" height="1417"/>
-            <value key="minSize" type="size" width="94" height="86"/>
             <view key="contentView" id="gIp-Ho-8D9">
-                <rect key="frame" x="0.0" y="0.0" width="507" height="413"/>
+                <rect key="frame" x="0.0" y="0.0" width="400" height="300"/>
                 <autoresizingMask key="autoresizingMask"/>
                 <subviews>
                     <openGLView useAuxiliaryDepthBufferStencil="NO" allowOffline="YES" wantsBestResolutionOpenGLSurface="YES" translatesAutoresizingMaskIntoConstraints="NO" id="DEG-fq-cjd" customClass="CSOpenGLView">
-                        <rect key="frame" x="0.0" y="0.0" width="507" height="413"/>
+                        <rect key="frame" x="0.0" y="0.0" width="400" height="300"/>
                     </openGLView>
                 </subviews>
                 <constraints>

OSBindings/Mac/Clock Signal/OpenGLView.m

@@ -48,15 +48,47 @@ static CVReturn DisplayLinkCallback(CVDisplayLinkRef displayLink, const CVTimeSt
 	CVDisplayLinkRelease(displayLink);
 }
 
+- (void)reshape
+{
+	[super reshape];
+
+	CGSize viewSize = [self convertSize:self.bounds.size toView:self];
+	glViewport(0, 0, viewSize.width, viewSize.height);
+}
+
 - (void)drawRect:(NSRect)dirtyRect
 {
 	[self.openGLContext makeCurrentContext];
 
-	CGSize viewSize = [self convertSize:self.bounds.size toView:self];
-	glViewport((GLint)0, (GLint)0, (GLsizei)viewSize.width, (GLsizei)viewSize.height);
 	[self.delegate openGLViewDrawView:self];
 
 	glSwapAPPLE();
 }
 
+- (void) awakeFromNib
+{
+	NSOpenGLPixelFormatAttribute attributes[] =
+	{
+		NSOpenGLPFADoubleBuffer,
+		NSOpenGLPFAOpenGLProfile,	NSOpenGLProfileVersion3_2Core,
+		0
+	};
+
+	NSOpenGLPixelFormat *pixelFormat = [[NSOpenGLPixelFormat alloc] initWithAttributes:attributes];
+	NSOpenGLContext *context = [[NSOpenGLContext alloc] initWithFormat:pixelFormat shareContext:nil];
+
+#ifdef DEBUG
+	// When we're using a CoreProfile context, crash if we call a legacy OpenGL function
+	// This will make it much more obvious where and when such a function call is made so
+	// that we can remove such calls.
+	// Without this we'd simply get GL_INVALID_OPERATION error for calling legacy functions
+	// but it would be more difficult to see where that function was called.
+	CGLEnable([context CGLContextObj], kCGLCECrashOnRemovedFunctions);
+#endif
+
+	self.pixelFormat = pixelFormat;
+	self.openGLContext = context;
+	self.wantsBestResolutionOpenGLSurface = YES;
+}
+
 @end