There are several ways to help make this project better:
testing and reporting;
translating user interface and documentation;
programming new features and fixing bugs.
Testing is what helps make applications rock-solid. As a community project, Fontmatrix relies on its users.
If you find a reproducible crash on Linux, generate a backtrace with gdb:
Install gdb.
Open a terminal.
Run gdb fontmatrix.
At the gdb prompt: run.
Reproduce the crash.
At the gdb prompt: bt.
Copy the output.
quit.
On modern KDE Plasma systems, KCrash and DrKonqi capture this information automatically and offer to file a bug report.
Submit reports to the issue tracker. A useful bug report contains: the steps that led to the bug; the backtrace if it crashed; and information about your system (distribution, Qt version, Fontmatrix version).