JComponent getGraphics() delivers a graphics context that
is not suited for drawing, which is contrary to what the
API states and the API documentation should be made consistent
with it. In Swing.JComponent.getGraphics() it is stated:

   "Returns this component's graphics context, which lets you
   draw on a component. Use this method get a Graphics object
   and then invoke operations on that object to draw on the component."

This is the opposite of:

   "None-the-less you should avoid, at all costs, grabbing the
   graphics and painting to it."