steps to reproduce :
* open a file
* make changes
* do an "undo"
* save your file
You can't do a "redo".
We (#netbeans on FreeNode IRC) just had a user asking about this issue as well; he's using: "Mac OS X version 10.6.2" and was having the same issues.
In order to check up on this I tried re-producing it on my own NB version, running Linux, and it does exactly the same.
I therefor changed the platform to "All" since this can be reproduced on Windows, Mac, Linux and just checked Solaris as well.
No comments on my part if this is a bug or a feature, just stating that its re-produceable.
Reproduceable at build 100331-eb8d22d7ddd4.
Issue added to NetFIX Pool . Module owner please speak up if you disagree.
*** This bug has been marked as a duplicate of bug 21237 ***