5th Fleet Damage infliction question

I am a newbie to VASSAL. I downloaded module 5th Fleet version 1.2.2. I encounterd a problem when trying to mark a counter as damaged. A window opens up and gives me a choice to “damage steps” or “can not submerge”. I try to enter values in either boxes, but I can’t figure out what key to hit for the window to close and apply the damage to the counter. My only option appears to be to close the window (in which case the counter is not marked as damaged).
Can anyone tell me what key I’m supposed to use for the window to accept my damage entry? Or if not, how do I disable this annoying feature and have the counter alternate between the undamaged and damaged side?

I still can’t figure out how to use the “Damage” feature, but I realize now that I may use the “flip” counter command to inflict damage the old fashioned way. If someone knows how to use the advanced damage feature, please let me know.