What causes Pinta to crash instantly when I begin image selection?
Solution 1:
Probably it's Mono problem and seemly v4.4.1 or older or dependently in some versions only.
Try once install/keep up-to-date the Mono by the following command (Ubuntu 18.04):
sudo apt-key adv --keyserver hkp://keyserver.ubuntu.com:80 --recv-keys 3FA7E0328081BFF6A14DA29AA6A19B38D3D831EF
echo "deb https://download.mono-project.com/repo/ubuntu stable-bionic main" | sudo tee /etc/apt/sources.list.d/mono-official-stable.list
sudo apt update
sudo apt install mono-devel
Or in older Ubuntu please follow instructions mentioned here.
Sometimes installing mono-runtime package would be enough to fix that.
You may also need to follow 3rd step in instructions and do Installation Verification.
If Mono was working fine then you should not have crash problems when using crop in Pinta as well.
You may need to try with different versions of Mono to get it to work.
Solution 2:
It is a known bug
Pinta constantly crashes in Ubuntu 18.04 fresh install
https://bugs.launchpad.net/pinta/+bug/1786822
Installing Mono MAY help (not guaranteed)
https://www.mono-project.com/download/stable/#download-lin
It seems like certain actions - for example drawing a selection box, clicking somewhere, then leaving Pinta for a bit, is a workaround for it not to crash. Not consistent enough to say with certainty.