When any additional option opens in the middle of the screen, it leaves the outline of its drop shadow after the dialog box has been closed. It will only go away if I completely restart my computer.

This is a major inconvenience and it's unreasonable to be expected to restart my computer every time I want to browse different options.

I've attached a screenshot showing the bug - I had the different stroke profiles opened. The issue happens when ANY option dialog box opens on the screen.