I noticed that what looks like a tooltip saying "Increase Indent" is floating homeless on my screen. Here it is with the edge of the browser window beneath it:
It has attained nearly infinite Z-order and sits above anything else I can move around, even Task Manager. (It does not superimpose over the lock screen)
How can I figure out which program owns this, so I can terminate it? I'd prefer to do this in a minimally invasive way - ie, not just reboot.
I have already closed certain applications just by guesswork but didn't luck into the offender. (Possibly, since this seems to be a bug, closed applications didn't actually clean up properly).
Searching for "increase indent" specifically floating like this didn't turn anything up, but I was hopeful this could be a commonly known issue.
I imagine there could be some utility (built in to Windows, or 3rd party) which might let you click on any UI element and identify its process?
Edit: I found the source of the tooltip, thanks to the answer below, which was a web app running in Chrome: