Shift-F12 opens dashboard slowly?

The symptom you're seeing (slow-motion Dashboard) is actually a hidden feature. For many of the OS X animation effects, holding down the Shift key shows the animation in super slow motion. Try Shift-clicking the minimise window button, or a Shift-clicking a minimised window in the Dock. The same is true for Exposé and others

The trigger, however is a bug. For some reason, turning off the F12 mapping in System Preferences works for plain F12, but Shift-F12 still goes through to whatever is mapped to F12. You can try changing the F12 designation (though turned off) to some other key, but I found that even this doesn't stop Shift-F12 going through to slow-mo Dashboard.

Apple needs to fix this.

BTW, as a workaround, you can probably change the keyboard mapping in Flash to not use F12, but another key instead by going to Flash > Keyboard Shortcuts...

The same is true for Edit Colours in QuarkXPress, which also uses Shift+F12.

How many times a day have I hit these keys, then hit my head on the desk a few times waiting for Dashboard to do it's slo-mo stuff before cancelling out of it and going back to Quark???

Very irritating!!

Try this..

Set the Dashboard shortcut to something else (F7, F8, whatever) the regular and slow mo' will switch to that key. Now, go back and disable the shortcut (set it to -)

May work even if you set to - directly, but I didn't try it, and probably can't go back to pre-test condition.

Note: This was done in Dashboard&Expose not Keyboard&Mouse prefs