I've been having exactly the same problem for a while now and havent really gotten around to fix it. I made a thread a while ago so maybe there might be some ideas in these you can try.
http://www.ozhonda.com/forum/showthr...ior-dome-light

However, when the tab is on auto function, there is a tiny little bit of light still coming through.

If you happen to find a solution, please share!