If you configure a panel launcher to have an empty tool-tip field, on a mouse-over the tool-tip tells you `this item is not been configured' which is both untrue and misleading.
Oh, dear, it seems the panel thinks it knows better than the user. That can't be right, can it? ;-) I have fixed the issue in SVN with revision 24104, so the next release candidate should no longer have this problem. Thanks a lot for the bug report.