@Override
        public void mouseExited(MouseEvent me)  {
			inside = false;
			setBorder(NO_BORDER);
			if (overrideBorder != null) {
			    setBorder(overrideBorder);
			}
		}
Mouse listener on the button to render it appropriately.
Ghidra/Framework/Docking/src/main/java/docking/widgets/SmallBorderButton.java