Even weirder: I've noticed that if I start typing before I click on the window, a small edit-box appears about halfway between screen-center and bottom-right-hand-corner, and my typing appears there.
It goes away if I try to do a screencap, so I can't show you exactly.
...but, like, what even is that? Where is my typing going to? Am I sending messages from there without knowing it? #wtf