Need OpenGL help -any experience?

I want to add a gradient background to qtvcp's Gcode graphics.
I can get it to show and zooming works but then rotation and panning doesn't.

I can't seem to get the right combination - i really have no experience with OpenGL so am just reading and hacking.
I'm hoping someone with OpenGL experience can look at the code - probably will see my mistake...

the most relevant code (from qt5_graphics in the qt5vcp_py2 branch) is this:



If I set self.use_gradient_background False everything works properly but no gradient background.
True and the background shows nicely but the panning and rotation are non functional.
Any help would be great.

Chris M