I regularly have to shift the location of my characters' bag windows as they creep "up" towards the top of the screen. Likewise every so often their bank bags' window locations "reset" and get all stacked up one on top of the other in a single location.

This sort of thing has been going on virtually since the game launched, and I've filed at least one or two in-game reports on it over the years. I'd really love to know what the status on this bug or set of bugs is.