Add sanity checks when adding key grabs
While fixing some issues in Orca related to the new keygrabs, I made a silly mistake somewhere which caused my keyboard to be completely locked up.
I have to work on some other tasks now, so I don't have concrete steps to reproduce the problem. But I suspect the problem was accidentally adding key grabs on some unbound commands. If AT-SPI2 is not already checking for a valid key string, perhaps that would be worth adding?
Let me know if I need to come up with an example procedure to completely lock up one's keyboard.