OK, I found it. The crash happens because of this line in my configuration file:
If you remove it or replace it to something like this, then everything is fine:
For some reason Synfig expects “pt” at the end of this line and it causes a crash in glibmm.
Packaged synfigstudio uses its own version of glibmm, that’s why the crash happens only for packaged binaries. If you compile form source, then your system glibmm will be used and no crash happen (though, tool parameter panel will display incorrect value for width radius - zero).
Big thanks to genete for helping to track this issue!
There are 2 ways to fix this:
- Provide updated/patched version of glibmm with packages
- Fix source code