As indicated in post 2970500, there doesn't "appear" to be a way of disarming the application via keyboard. When I activated the alarm via the Menu bar, my screen went completely black with the logo appearing. I had no instructions or any way of knowing how to deactivate the alarm via keyboard, especially since the keyboard and mousepad are alarm triggering options. It was seem that a dialog box would be appropriate, as you mentioned considering, or not have the keyboard or mousepad activate the alarm. Secondly, if the keyboard is the current way to deactivate the alarm and there is no dialog box, what happens if I slip and hit the wrong key? Am I screwed? And yes, shutting the screen was the only way to shut the alarm off by making the computer go to sleep...opening the screen caused the Alarm to reactivate. I had to hurry up opening the screen and hold down the power button to reboot.
MacBook Pro 10.6.3