The cancel button currently permits the current operation to continue, rather than actually stopping it. In case of computationally intensive opertations, this causes the application to become non-responsive for very long times, which wastes a lot of time. In may cases I personally opt for forcing the whole application to be shutdown at system level, instead of waiting endlessly for the current operation to stop.
Hi @artur.krukowski as you mention, processing can be resource-intensive and interrupting processing as well. If PIX4Dmapper freezes and you anyway want to interrupt processing, the best way out for the moment is indeed to force PIX4Dmapper to close. Cheers