fix copying images to clipboard randomly failing

BUG:480448 BUG:509689 BUG:505281 BUG:509065

this fixes/works around the issue by copying the image before closing the fullscreen window

Draft because this breaks the "image copied to clipboard" inline message that appears at the top of the window, need to figure out a way to fix that (@ndavis any help on the best way to fix that?) (i fixed that but not sure if its the best way to fix it since i'm not too familiar with the codebase)