The cause is that the mask is splitted with the buttons instead of being separed.
In fact if you change disposition (minimize,maximize,close) the bug is the same.
A solution is to separate the mask from the buttons.
The cause is that the mask is splitted with the buttons instead of being separed.
In fact if you change disposition (minimize, maximize, close) the bug is the same.
A solution is to separate the mask from the buttons.