Qt Creator has much painting code which misbehaves under HighDPI scenarios and produces bothersome artifacts.

Here a small selection:

1. "Fancy" widgets have several off-by-ones which create gaps and overlaps
   
2. The cursor in the binary editor leaves traces when selecting data
   
3. The ColorTip in the QML editor has a misplaced outline
   
4. The MiniTargetSelector has several misplaces outlines