A JButton is only "down" while it being pressed with the mouse or keyboard space bar (or
maybe the enter key if it is the default button in the JRootPane). For an AbstractButton
that will hold selected state you can use JCheckBox or JRadioButton in addition to
JToggleButton. Otherwise, use a boolean flag as a member variable in the enclosing class to
keep the "selected" state for you. In other words you have to come with a way to do this on
your own.