how to stop wait state of imroi

hi dudes,

i have designed a GUI which includes a circle button and a rect button. in rectbutton callback ,imrect is called in a loop while rectbutton state is on and imellipse is called in the same way in circlebutton callback. now the problem is when i click for example on circlebutton and then click the rect button both imrect and imellipse are active and both shapes are drawn how can i exit imrect (or imellipse) function when its in the waitfor state?

thanks