How to tell if the mouse is over the stage?

I have a “scrolling image” type Flash project where I move an image that is larger than the stage around based on the location of the mouse. All that works fine, however I still get the scrolling action when I move the mouse off the stage. When I move it off of the stage (and on top of the html page, or anything else on my screen), I’d like for the scrolling to immediately stop. For some reason Flash hangs on to the last known mouse position (over the stage) before it goes off the stage so it continues to use that in the scrolling code.

Is there an easy way to simply determine: Is my mouse over the stage?

Thanks.