I don't know, but my random guess would be that it might be to handle quirks with certain events like drag-and-drop or scrolling, which need to be handled reaso

I don't know, but my random guess would be that it might be to handle quirks with certain events like drag-and-drop or scrolling, which need to be handled reasonably when a process suddenly opens a window under the one you're using. Not sure what such a quirk might be though.