Steps to reproduce:
1. Open SimulIDE
2. Drag AVR microcontroller atmega328 to schematic
3. Right-click component and click "Open Serial Monitor"
4. Close serial monitor window
Result: SimulIDE crashes.
Same occurs when opening a project saved while serial monitor window was open, if I close the serial monitor window SimulIDE crashes.
Tested on x64 Linux.
EDIT: Same issue as reported by user wallysalami in the thread "Simulide crashes on serial monitor", but different from issue topic starter TimFisch had (which should be fixed in 0.5.15-RC2).