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tofro
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Basically all graphical user environments (MS Windows [1985], X11 [1984], Atari GEM [1984] send a running application a list of screen regions that need to be re-drawn when one of this application's windows is un-obscured (This list of screen regions is typically attached to some sort of WM_PAINT message).

It is up to the application wether it goes the hard way and only updates the parts of its windows that actually need an update, or wether it decides to go easy and collapses all these regions and redraws all of its window area.

So this standard technique is built in practically all WIMP environments that showed up in the early 1980s.

tofro
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