124 Manipulators and Spacemouse support

    When a manipulator receives a SoSpaceballButtonEvent::PICK event,
    it should check if it has been picked and activate itself,
    starting to listen for and react to spaceball events
    (SoMotion3Event and SoSpaceballButtonEvent).

    20040722 larsa

    UPDATE 20040909 mortene: the relevant draggers should react to
    SoMotion3Event events after any type of pick that started the
    dragger interaction, not just of the spaceball-variety, methinks.

    For convenience, should perhaps SoDragger::handleEvent() react to
    SoMotion3Event and invoke the motion callbacks in the same manner
    as it does for SoLocation2Event? (The alternative option is
    probably to have the relevant draggers set up a callback with
    SoDragger::addOtherEventCallback() and each do their particular
    processing.)
