Dunno if this one's been reported yet, but ot seems that grabbing tiles from a qst file while in large mode causes the loading screen to popup and then it leaves part of itself behind the grabber window once it closes. Here's a screenshot to show it: http://www.questwizard.net/files/zqlrg-qstgrabglitch1.png
EDIT: Forgot to mention, it only does this sometimes, but not every time. I'm not entirely sure what causes it to happen myself.