When renaming or moving package containing GUIDesigner forms, images and nested forms paths inside the forms are not updated.
The form containing nested forms becomes invalid as a result and its xml should be edited manually to fix the problem. Try to do it on 30 forms and you will probably understand why it seems important to me.
The bug is reproducible from IntelliJ 6.0(build 6180) up to 7576 build of IntelliJ 7.
Usability suggestion:
When path to nested form becomes invalid, all form is considered invalid (would be better to replace invalid nested form with panel and enable to update the path manually, the way it works with images)