Created attachment 133325 [details]
Screenshot 1

NetBeans 201302132200
JDK 7u17

I have seen this randomly happen before, but for the first time I have now noticed a pattern. :) Steps to reproduce:

1. Create a new NetBeans platform module (I used an Ant-based one).
2. Create a new Java class in the module.
3. Add a method with some code to it, and add a breakpoint. 
4. Create a new sub package.
(Everything should work as expected up to this point.)
5. Now move the class, breakpoint and all, to the new package.
6. The icon in the margin of the editor indicates that multiple breakpoints are on the line, yet the breakpoints window shows only one. (Screenshot 1 to be attached here.)
7. Toggling the breakpoint by clicking on the icon in the editor's margin just changes the presentation to that of a single exception in the editor. The Breakpoints window doesn't show it anymore. (Screesnhot 2)
8. Only after restarting the IDE will the presentation return to normal in the editor, i.e. no breakpoint shown there either.