@Override
		public void focusGained(FocusEvent e) {
			if (!haveFocus) {
				haveFocus = true;
				fireFocusListeners(e);
			}
			state.whichFocus = linked.index;
		}
A listener for all my callbacks

<p>
A separate listener is constructed and installed on each field so that we have a reference to
the field in every callback.
Ghidra/Framework/Docking/src/main/java/docking/widgets/textfield/TextFieldLinker.java