Esc and Enter are handy for closing the synchronizer window and starting the compare (respectively).
However they are also too easy to press.
It is annoying to accidentally hit Esc or Enter and start the compare from the beginning again, especially after making several per-file direction adjustments.
This patch disables the Esc and Enter keys after Compare has been started for the first time.
You can still close the synchronizer window via the system window menu (or shortcut), and you can still restart the compare via ALT-M