Workbench: hide background option for OpenGL render

When OpenGL renderer is selected the option for background colors are
displayed, but ignored. For now we hide this option as it makes no sense
to have a viewport color option without viewport or render a 'final'
with a theme color.

release/scripts/startup/bl_ui/properties_render.py

@@ -853,7 +853,7 @@ class RENDER_PT_opengl_color(RenderButtonsPanel, Panel):
         return (context.engine in cls.COMPAT_ENGINES)
 
     def draw(self, context):
-        VIEW3D_PT_shading_color.draw(self, context)
+        VIEW3D_PT_shading_color._draw_color_type(self, context)
 
 
 class RENDER_PT_opengl_options(RenderButtonsPanel, Panel):