In the Mac glass code the routine _setWindowFrameWithRect:withDisplay:withAnimate: behaves differently whether it's called from _restorePreZoomedRect or not. It determines this by directly inspecting the Objective-C call stack i.e. it calls NSThread.callStackSymbols and looks at the top of the stack. Maybe I'm missing something but as these are all internal calls it would be far cleaner to add an additional parameter to _setWindowFrameWithRect. In any case this requires some additional investigation.