@Override
	public void dispose() {
		if (fileOpenDropHandler != null) {
			fileOpenDropHandler.dispose();
			fileOpenDropHandler = null;
		}
		super.dispose();
	}
We need to do this here, since our parent constructor calls methods on us that need the 
extension manager.
@return the extension manager
Ghidra/Framework/Project/src/main/java/ghidra/framework/project/tool/GhidraTool.java