If you hack your camera and then expect it to work perfectly you should probably have thought more about hacking your camera. There are some tradeoffs when hacking the camera. Stability and usability are some of those trade-offs.
I don't have a hacked GH1. However, I have a hacked GF1. There are two options for the GF1 manual video controls in the GF1 PTOOLS. One of them turns certain modes into video only modes. The other one requires the user to select the manual mode in the menu to toggle whether it is video only or not. I am not sure if the GH1 works in the same fashion. If it does that may help. If this really is a big deal for you then you should probably just unhack the camera and use it the way Panasonic warranties it.