I'm having trouble doing something pretty basic:

I want to have a form with two buttons on it: Start and Stop

When one pushes 'Start', a background process starts that performs a continuous loop, looking for files in a particular directory, and copying them to another if they exist. In order to stop this sentinel process, one would press 'stop'.

However I write the code, the focus seems to remain with the background endless loop, and I can't get the 'stop' button to work.