How to fix: RubyMine does not remember last used monitor (on Ubuntu)

Every time I started RubyMine, it opened the main window on the left monitor -- when moving it to the center monitor and closing it, the next time it still opened up on the left one.

Here is how I forced RubyMine to start up on a different screen:

1. Un-maximize the main window
2. Move it to your preferred monitor
3. Close RubyMine (keep it unmaximized)
4. Start RubyMine again.
5. You may now maximize your main window; the next time you start up RubyMine, it will open on the correct screen, maximized.

That's crazy!