private void ungroupSelectedVertices() {
		graphCollapser.ungroupSelectedVertices();
		if (!graph.containsVertex(focusedVertex)) {
			focusedVertex = null;
		}
	}
Ungroup the selected vertices. If the focusedVertex is no longer in the graph, null it. This
will happen if the focusedVertex was the GroupVertex
Ghidra/Features/GraphServices/src/main/java/ghidra/graph/visualization/DefaultGraphDisplay.java