how to make usable controls even when there is some loop running under them?

Question

I am doing a simple windows application. I have used only a few controls, only three buttons. Each button has some loop that runs each time I click on the button. sometimes the loop lasts and I think to use another button to stop the loop. The problem is that during the time the loop runs I can not use any of the controls, none of the buttons can be clicked. They are ready to use only after the loop ends.
Is there any way to make the controls, in my case the other buttons, usable even when there is some loop running in my application?