When a window is created with the FramelessWindowHint flag (in my test it's a QFrame), it shows a title bar (with close/max/etc buttons) while it should just show a plain rectangle without any decoration. This is a regression.
This happen with http://download.qt-project.org/snapshots/qt/5.2/5.2.0-rc1/2013-11-20_159/
It doesn't happen with http://download.qt-project.org/snapshots/qt/5.2/5.2.0-rc1/2013-11-13_147/
Probably caused by this patch: https://codereview.qt-project.org/#change,71388
Coming from this: https://bugreports.qt-project.org/browse/QTBUG-33011#comment-222511