When sizing demo7 (the same with other demos, demo6, demo8, font demo) app window to fullscreen you will see any of the window's transparent part become like this:
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In fact, after some test I find these 'mess' (I dont know which word to use) will show if the windows have alpha channel part after resizing.
like this:
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
The window will back to normal if you have mouse move in them or drag them to move.
But it's unacceptable because resizing the application window is a usual operation.
Anyone meet the same issue?
Can we solve it?