Toplevel window move jitter on OSX

The following lines in qwidget_mac.mm cause (IMHO) unacceptable jitter when programmatically moving a toplevel window:

4543    // The window is moved and resized (or resized to zero).
4544	// Since Cocoa usually only sends us a resize callback after
4545	// setting a window frame, we issue an explicit move as
4546	// well. To stop Cocoa from optimize away the move (since the move
4547	// would have the same origin as the setFrame call) we shift the
4548	// window back and forth inbetween.
4549	cocoaFrameRect.origin.y += 1;
4550	[window setFrame:cocoaFrameRect display:realWindow];
4551	cocoaFrameRect.origin.y -= 1;
4552	[window setFrameOrigin:cocoaFrameRect.origin];

To reproduce, simply create a toplevel window and implement the appropriate mouse event handlers to move the window from a mouse drag in the client area (as opposed to the native title bar). The resulting move will oscillate +- 1px because of the code above, resulting in unsightly jitter.

Moving windows in this fashion is a requirement for toplevel frameless windows which implement their own title bars and window decorations (ala google chrome).