[ENHANCEMENT] Movable lights in 3D Model Import dialog/Material Editor
Currently the 3D light in the 3D Model Import dialog shines "through the camera lens." This provides a fairly flat lighting which is pretty good for judging Diffuse and Specular colors, and, to a certain amount, reflections.
However, it's utterly useless for adjusting things like Fresnel - literally useless, since Fresnel covers how apparent color reflects with changing angle of incidence between light, object and camera.
Since mouse drags rotate the object in 3D space, I suggest adding an icon to the viewer. Click+hold+drag on this icon would rotate the light on the X/Y axes.
Icon could look something like this: