When trying to cancel the "generating mesh" processing in batch processing mode, PhotoScan 0.9.1 (and I believe also earlier versions) asks for confirmation but then keeps on processing. Pressing Escape or clicking on the "close" button in the upper right corner of the batch processing window has the same result - I can't stop the processing. When pressing "Pause", the button becomes inactive for half a second and then becomes active again; the processing doesn't pause.