This Bugzilla instance is a read-only archive of historic NetBeans bug reports. To report a bug in NetBeans please follow the project's instructions for reporting issues.
Normally you can use undo and redo functions just fine. But when you undo something and save a file, all redo options will be gone. Undo will keep performing previous operations. It's really annoying when you want to compare some changes (like deleting some part of the code to debug it) or simply undo and save a file involuntarily.
*** This bug has been marked as a duplicate of bug 21237 ***