@slbaumgartner said:

Drifting off topic a bit, but I've always thought the materials editor on Mac was driven more by reuse of the standard Mac OS color UI than by an effort to provide a useful tool in SketchUp! The concepts just don't quite line up, and it results in a very awkward SketchUp tool.

further, sketchup hijacks the osx 'color palette' which is the one with a list view.. renames it to 'texture palette' and takes away the list capability.. this is especially problematic when a model has different materials of similar color yet varying properties (such as black leather and black shiny paint in the same model.. there's no simple way to differentiate between the two via the color picker)

the color picker elsewhere in osx has a list view palette.. sketchup cancels the ability.

This one-liner copy/pasted into the Ruby Console + <enter> will return the angle [in degrees] between any two selected faces [just preselect 2 faces before using it]

s=Sketchup.active_model.selection;a=s[0].normal.angle_between(s[1].normal).radians

You can use it to form the basis of a tool...
You could have the tool let the user pick 2 faces instead of the s[0] & s[1] and a dialog shows the angle, or pick an edge and if the edge.faces.length==2 use those two faces instead where 'edge' is s[0] then use a=s[0].faces[0].normal.angle_between(s[0].faces[1].normal).radians etc...