Qt5: resize or animation of QMainWindow causes flicker

[rfw21]

Hi forum

I've been upgrading a project from Qt 4.8 to 5, and have noticed one change/regression.

I use a QPropertyAnimation on the geometry to a QMainWindow to resize it. This works perfectly in Qt4, but in Qt5 causes awful flicker on both Mac and Linux platforms. (Haven't tested Windows).

Additionally I've noticed that even resizing a QMainWindow (without an animation) now causes a noticeable flicker, as if the entire underlying NSWindow is removed and then redrawn, briefly revealing the content beneath it.

Any ideas what has changed to cause this? And is there a workaround or fix?