I don't know of a way to detect when the windows default input device has changed. It might be possible using polling. In other words, every once in a while (could be every two seconds or whatever) check the registry to see what is the default microphone. The more often you check, the more you are wasting your computer resources, and the less often you check, the longer it will take to detect a change, when it occurs.
It is not very elegant but it might work. VoxCommando currently using polling (3 seconds) to detect which program has focus. I don't like it, but it seems to work fine.
I believe there is a way in eventGhost to check a registry value, so yes, this could be done with EventGhost and a python script... probably.
The first step would be to find the correct registry key and to verify that it does actually change when the default input device has been changed.
In the case of Mobiola though, I don't think there is any way to detect it because the default windows device is not actually changing. I think they are internally passing through to the other device, and I have also found that is does not work very well, at least not on my system.
