When dragging for resize geometry or main window, window flashes

[tkbd]

I just want to know if this problem is still present in the current version.

At first,I will talking about current MacOS environment.
There were also several updates on OSX 10.11.6 later(but no change version number).
For example Some changes have been made to Intel's drivers by Apple's Security Updates.
But I don't know whether it brought to good affect to this problem.

Based on them,
The flicker when moving the vertical frame bar was reduced apparently!
( Flickers were reduced as amount same as when horizontal bar moving for up and down.)

And, when window size changed that it still occured flicker.
But It wasn't also as intense than screen capture recorded before.

I think that a slightly better impression than before.

OSX 10.11.6 + Some updates
Wings3D 2.1.5
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tkbd