The activate button is just silly for configuration in retrospect. It's
confusing to users, and was even confusing to some other developers.
Instead of using an 'Activate' button for game capture every time you
want to capture a window, just make the 'window' list have a default 'no
window' value (empty), and then have it always active when an actual
window is selected. The way syphon handles this on mac is actually
where I took the idea from (as suggested by Palana).
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