This one is kind of hard to explain...
When running ZQuest scaled, say.. 2x. Your mouse still thinks ZQuest is still scaled at 1x.
For example.. Under Linux, load up ZQuest using scale 2, (Thanks to ZCL) and try to access the edit menu.. You can't, until you move your mouse arrow OFF the ZQuest screen.
For a screenshot, (Though, it may look strange) See the attachment. I simply clicked where the mouse is, and that's where the ground tile showed up.