I have a Userform which contains two buttons. One buttons
says "Begin" and the other button says "Cancel".

If the user presses "Begin", my macro will begin processing a
potentially long computation. Once the computation begins,
can I allow the user to press the "Cancel" button to break
out of the big computation?? Is that possible?

Additionally, is it possible to display some sort of progress
bar to display a percentage which shows how much of the
computation is complete? Would I need some sort of plug
control for this? Or can I just simply update a text label on
the form to show percentage completed??

Thank you!