Pico-8 on Linux is having problems in full screen mode. When launching full screen, 3 out of 4 times the screen flashes and the programs sits in the background, but can't be accessed and has to be killed. The same thing happens when switching from windowed to full screen mode. Everything works fine in windowed mode.

It seems like this was a problem back in 2016, but was reported fixed. However I am experiencing this in 2021 on Ubuntu with the Xfce desktop environment.

fullscreen has been working fine for me ever since that was fixed and I'm on Ubuntu 20.04 (standard Gnome 3-based version) now. Maybe it's an Xfce-specific issue? Also what version of Ubuntu are you on?

I'm on Ubuntu 20.10. And if it makes any difference I'm on Xfce 4.14.

Can you try with the pixel_perfect option?

I’ve also read in other threads that the blitting option may help but I don’t understand what it does.

I didn't know about these options, but I have now tried them but they have no effect.

When I try to boot Pico-8 in full screen, it's like the task doesn't complete. In my task manager program, the tast is listed as literally the run command "pico8 -pixel_perfect 1". On the occasions where it does boot correctly, it is listed as just Pico 8 with an icon next to it. Also, if I try enough times, eventually my desktop environment gets corrupted and I have to reboot to restore functionality.

Is it different if you boot in windowed mode then switch to fullscreen (Alt-Enter)?

No, it's no different. Occasionally it works, but generally it doesn't.

I figured it out! Turns out I needed to set fullscreen to mode 2 in the config file:

fullscreen_method 2