from chimerax.mouse_modes import MouseMode
class PySideCrashMode(MouseMode):
    name = 'pysidecrash'
    def mouse_down(self, event):
        # This crashes PySide 6.10.1
        print('%d' % (1,2))

session.ui.mouse_modes.bind_mouse_mode(mouse_button = 'right', mode = PySideCrashMode(session))