It is the ButtonThrower object that is responsible for sending messages like “control-n” and “n-up” in response to keypresses, and for monitoring the state of the shift, control, and alt keys with respect to those events. The MouseWatcher object, on the other hand, is responsible for monitoring the state of the control key as it influences the trackball or whatever, but not for generating event names.
It was actually my mistake to recommend calling only mouseWatcherNode.setModifierButtons() in the above post; the correct fix is to call it on both the mouse watcher and the button thrower.
David