STEPS TO REPRODUCE 1. open an image file in nomacs - https://nomacs.org/ 2. grab the image in nomacs' window to initiate drag and drop 3. close nomacs without dropping the image OBSERVED RESULT A thumbnail of the image gets stuck in front of all other windows and it can't be removed. EXPECTED RESULT thumbnail gets discarded when nomacs quits
Wayland or X11? How are you quitting it? Ctrl+Q with one hand while the other hand drags it using a mouse/touchpad?
(In reply to Nate Graham from comment #1) > Wayland or X11? > > How are you quitting it? Ctrl+Q with one hand while the other hand drags it > using a mouse/touchpad? X11, I didn't try it on wayland. Both clicking on the close button and alt+f4 have the same effect, but what I just noticed is that the nomacs process is still running in the background when this bug happens and if you terminate it the leftover thumbnail disappears - so I don't know whether it's kwin or nomacs bug, which of the two is responsible for ending drag and drop operation in this case.
Out of curiosity, how are you using the cursor to drag the image, while also using the cursor to click the close button?
(In reply to Nate Graham from comment #3) > Out of curiosity, how are you using the cursor to drag the image, while also > using the cursor to click the close button? Click with left mouse button and drag the image until you see a thumbnail appear and then let go left mouse button - the image thumbnail stays with the cursor. It actually is weird because the thumbnail stays within the nomacs window and can't be dropped that way on to other apps. Dragging works properly with left mouse + ctrl.
Got it. Since this is on X11, it's an issue in the app or the X server, not KWin. You'll want to follow up with the app's developer.