I have a thunderbolt dock at my desk with an external screen and a bunch of USB peripherals hanging off it (USB keyboard for example).  I also use a Bluetooth Magic Mouse at the desk.  When I start Picard in this set-up everything works fine, right-click on the MM and the trackpad both bring up context menus.

When I disconnect from the dock and unpair/turn off the MM, Picard no longer does anything when I right click.  Restarting Picard fixes the issue.