Sadly, but suddenly, the "prtsc" button stopped working with the Linux Version of OpenXcomEx in full screen mode so a few turns got lost until I realized that something is amiss. Noting really fun was lost though. A Mongorn walked up to the crew, the dog somehow failed to bark it to motionlessness (huh, this is a real world that spellcheck recognizes) and instead bit it to death. Will try the Windows version with wine. It might even work.
I recently updated to Ubuntu 20.04 (why, just why) and, uhm, I updated something else since midday so some parts are misbehaving (working as the developers intended) as usual.
If the above makes no sense, I blame my English and love for long sentances.
EDIT: Problem resolved by using F12 for screenshots, but now GIMP refuses to draw red on the picture and defaults to some weird colors. So uhm, not really resolved. Ahhh, the majestic world of computer problems. See pic 1 below. I tried drawing the arrow red as usual.
EDIT2: The above problem is resolvable by going in the menu Image->Mode->RGB. It was set to Indexed so I presume the game saves screenshots in the format that it uses. But I am not sure I want to make that many more clicks for every picture.
EDIT3: Nope, restarting doesn't fix it. But using wine did the trick.
EDIT4: Sadly, the X-COM way of solving problems (with High Explosive and Large Rockets) will not work. I would like to try, but don't have real life access to it.
