Resizing windows on mac results in red blips as display is flipped

[connorjclark]

ex_draw2 exhibits this: https://youtu.be/6UJNHFO4myU

I forget now, but this may only be for Debug build (red suggests a common debugging memory value) and results may vary for Release.

[SiegeLord]

There is now a workaround for this implemented in #1442