code: private void updateRegion() {
  		actMessagePanel.setVisible(false);
  
  		if (rbtACT.isSelected()) {
  			actMessagePanel.setVisible(true);
  			regionFields.setVisible(true);
  			regionSelector.setOptions(new String[]{null, "Belconnen", "City", "Woden"});
  			regionSelector.setVisible(true);
  		} else if (rbtNSW.isSelected()) {
  			regionFields.setVisible(true);
  			regionSelector.setOptions(
  					new String[]{null, "Hunter", "Riverina", "Southern Tablelands"});
  			regionSelector.setVisible(true);
  		} else if (rbtVIC.isSelected()) {
  			regionFields.setVisible(true);
  			regionSelector.setOptions(
  					new String[]{null, "Gippsland", "Melbourne", "Mornington Peninsula"});
  			regionSelector.setVisible(true);
  		} else {
  			regionSelector.setOptions(new Object[]{null});
  			regionSelector.setVisible(false);
  			regionFields.setVisible(false);
  		}
  	}
docs: Updates the visibility and options present in the region selector, depending on the state selector's value.