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I use KDE Desktop with KWin
The default gpu is Amd integrated
I was wondering if its possible to re enable the compositor when a full screen window is inactive without disabling blocking the compositor
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You could do a script that checks the active window and then uses KWin's DBUS interface to dis-/reenable the compositor. Not on my Arch so a bit difficult to provide specifics, but this should generally be possible.
Alternatively consider testing a Wayland session where you can't disable the compositor but also don't have many of the drawbacks you have on Xorg from this being the case.
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