Implement right mouse click on OS X when pressing control + click. This

restores the previous mouse behaviour as found in LWJGL 2.8.5 and below.

src/native/macosx/org_lwjgl_opengl_Display.m

@@ -57,6 +57,9 @@
 
 static MacOSXPeerInfo *peer_info;
 
+static bool leftMouseDown = false;
+static bool rightMouseDown = false;
+
 @implementation MacOSXKeyableWindow
 
 + (void) createWindow {
@@ -348,6 +351,13 @@ - (void)mouseButtonState:(NSEvent *)event :(int)button :(int)state {
 }
 
 - (void)mouseDown:(NSEvent *)event {
+	if ([event modifierFlags] & NSControlKeyMask) {
+		rightMouseDown = true;
+		[self rightMouseDown:event];
+		return;
+	}
+
+	leftMouseDown = true;
 	[self mouseButtonState:event :0 :1];
 }
 
@@ -360,7 +370,15 @@ - (void)otherMouseDown:(NSEvent *)event {
 }
 
 - (void)mouseUp:(NSEvent *)event {
-	[self mouseButtonState:event :0 :0];
+	if (rightMouseDown) {
+		rightMouseDown = false;
+		[self rightMouseUp:event];
+	}
+
+	if (leftMouseDown) {
+		leftMouseDown = false;
+		[self mouseButtonState:event :0 :0];
+	}
 }
 
 - (void)rightMouseUp:(NSEvent *)event {