Toggle for displaying a specific texture on the model

[itsallgoode9]

Many times it's very helpful to see something that is NOT the diffuse texture on your model in the viewport (maybe you're working on spec maps or normal maps and want to see that) or in the case of using mix materials, no texture show in the viewport at all.

In all texture nodes, (or maybe in the model attributes?) it would be good to have a a "force display texture" checkbox that would force maya show that specific texture on the model in the viewport. Having to map spec, normal, etc textures through the diffuse slot to be seen in the viewport is really a pain in the ass, time consuming and really opens up the door for errors.