Problem with normal map display in glsl texture paint mode Looking through past posts I see this problem has been addressed often. I have tried many of the offered solutions unsuccessfully. I have a hi poly sculpt that I have normal mapped to a lower poly object. I would like to see the effect of that normal map while painting in a diffuse color slot in texture paint mode. The map looks fine while in the render viewport setting but does not show up in any other viewport setting. Painting while in a render viewport is too slow and not a viable option. To check my basic settings I made a simple scene with a plane object normal mapped with a sculpt and was able to see the mapped result fine in texture paint solid or texture viewport. So it seems the process does work but I cannot get it to work on this particular file. Is there a poly count limitation at work here or am I totally missing something obvious? Please see attached images demonstrating this issue.
Textured shaded mode may be what you are looking for.  It's shown in the animated image below.  Sorry about the messy .gif.  Apparently LiceCap really does not like Texture Painting.

To use this viewport shading mode with normal maps, you should add some lighting or all you will see is a sold black model.