protected boolean checkForVertex(MouseEvent e) {
		if (!checkModifiers(e)) {
			selectedVertex = null;
			return false;
		}

		VisualizationViewer<V, E> vv = getViewer(e);
		selectedVertex = JgtUtils.getVertex(e, vv);
		if (selectedVertex == null) {
			return false;
		}

		e.consume();
		return true;
	}
Checks the given mouse event to see if it is a valid event for selecting a vertex at the
mouse location.  If so, then the vertex is selected in this mouse handler and the event
is consumed.
@param e the event
@return true if a vertex was selected
Ghidra/Features/GraphServices/src/main/java/ghidra/graph/visualization/mouse/AbstractJgtGraphMousePlugin.java