Back in Wildfire days, it used to be possible to have tangent edges show as dimmed in shaded view.
Apart from looking nice, this allowed you to simultaneously tell whether an edge was tangent or not, and also check all your edge lengths between rounds and other surfaces when constructing complex surfaces.
Since Creo, tangent edges in shaded view can either be completely off, in which case you can't see edges lengths between tangent surfaces; or 'hard', in which case you can't tell the difference between a tangent and non-tangent edge - unless you work in a wireframe-type view, in which case you can't see the shape of surfaces.
Yet another piece of lost functionality in the downgrade from Wildfire to Creo... please can we have it back? I can see no reason for making this feature non-functional!