Blender Git Loki

Fix T43208 material flickering in edit mode.

Happens because material setting now occurs in the derived mesh drawing
routine as it should. However that means that it also happens during
selection and that influenced the drawing state somehow.

In 2.72 this did not occur because material setting happened during draw
setting (skip or draw) instead of after the draw setting passed (so
selection would skip it by use another draw setting function). Of course
this violated design but worked.

Made it now so backbuffer selection does not enable materials (it's
redundant in those cases anyway).

This could be ported to a possible 'a' release but as is classic with
display code there may be some other places that it could backfire.

Tested fix with texture/vertex painting and selection which use
backbuffer for both subsurf and regular meshes and it seems to work OK.