This is more of an irritation than a bug, but worth mentioning:
I've been running Diana on the secondary monitor screen of a 2 monitor system (in my case it's to the left of the main monitor, so the X ordinates are -ve). Once the main screen and all the dialogs are moved onto the secondary screen they are fine, and stay there across sessions, but some messages don't appear to be anchored to a movable display component, so consistently appear on the main monitor screen, and can't be moved (no drag feature). An example of this is the 'Not found' message returned by a failed editor search (e.g. "foo" not found, press Shift+F3 to search from the top). This consistently appears at the bottom left of the main monitor, and can't be moved.
It would be really nice if all floating messages, that are not independently movable, were anchored to the IDEA main frame or other IDEA window, or used the same virtual screen (GraphicsDevice) as the IDEA main frame, so they would appear on the same monitor.