Thanks, that pointed me in the right direction--and sorry I left out a piece of information: I was using the Trackpad, not an actual mouse.

The fix is to enable "Secondary Click" in the System Preferences (You have an option of left or right corners of the Trackpad). OSX then behaves like Linux (The context menu staus up as long as the right button is held down; releasing the button over a popup menu item activates the item).

I then belatedly tried the app with an actual mouse and the right button click worked as expected--regardless of the "Secondary Click" setting.