If auto_render is true the render
signal will be emitted every time the widget draws.
This is the default and is useful if drawing the widget is faster.
If auto_render is false the data from previous rendering is kept around and will be used
for drawing the widget the next time, unless the window is resized. In order to force a rendering
queue_render must be called. This mode is useful when the scene changes
seldomly, but takes a long time to redraw.
| this |
a GLArea |
| auto_render |
a boolean |