It’s possible to hide the title bar within in a Quicktime player X window. The titlebar automatically shows up when the mouse pointer is active in the window. To disable this behavior, quit Quicktime X and apply the following command:
defaults write com.apple.QuickTimePlayerX MGCinematicWindowDebugForceNoTitlebar 1
Revert to default setting with:
defaults write com.apple.QuickTimePlayerX MGCinematicWindowDebugForceNoTitlebar 0
