Hey! This is pretty neat! Here's what happens on my game (in case you wanted to know what happens on different projects):
Battle was speed up through the roof!

Message text would not begin appearing until you hit the OK button, when it came all-at-once.
As long as the button was held down, no scene changes or teleports could occur (try tapping F12 with this while it tries changing maps. It looks really funny.)
In the map scene (sometimes) animations would appear, but they wouldn't actually animate. It would just show the first frame and stop. Curious.
But yea. Pretty neat! ;D Now all we need is a way to stop F1 and F2...