The Left Control key is mapped by default to use magic
so long as it's held down. Unfortunately, Ctrl+F5 is
also the key for the GMM. I was having issues with,
for example, opening the GMM and loading a savegame
where the end action for magic wouldn't fire, and it
would keep draining magic away. Now, I use the
pauseEngineIntern to explicitly disable all key flags
when the GMM is opened, ensuring magic is turned off.