If you are experiencing this, you can alleviate the problem in 2 ways:

1: If you are using the application in a way that leaves you some spare desktop area, disable the 'Force Mouse Capture' option in the 'Configuration & Tools' -> 'Configuration' -> 'Display' (see notes next to the button)

I tend to have this always disabled, but its enabled by default. You can then re-capture the mouse etc, by clicking outside of the application.
NOTE: though, it does mean that if any of the interface that ends up overlaying the GNOME top-bar & launch-bar will not work! as GNOME takes over the mouse event for those areas in this mode.

2: Additionally, run the application in Window Mode (option in same configuration area) to help gain control outside of the application if it locks up. You can use the window bar to move the application out of the way to get to the desktop underneath.

Finally report how to reproduce the crash/lockup and hopefully I can resolve then problem.