Stop movie randomizer


I have several ‘buttons’ that blink randomly using this function:

function movieRandomizer(){
      num = Math.floor(Math.random()*14)+1
      movie = "mc" + num;


setInterval(movieRandomizer, 500);

What I would like to do is to stop the randomizer from playing on the button that is pressed/active and when the button is clicked again to stop the animation it controls, to continue to randomly blink with the other buttons…

Attached is a test .fla for y’all to look at, only the 4 purple buttons on the bottom are clickable (don’t go any where yet…). The clicked/active state is when the button is glowing…

Any help would be great! Thanks.