>I want to do a particular function on a grid. Under normal circustances the function can only be done once without selecting a particular option on the form to enable the function. However, under certain situations I want the user to be able to repeat the function if they wish. I would like this to be done by pressing and holding a keyboard key, say F3. As long as the key is pressed the function will process without extra user interaction. Can someone help with this?

You want to say the this function will be executed until the user hold the F3 down? And when S/He free the key you want to stop this function somewhere in the middle?