Uh, I think maze means "Display > Polygons > Border edges", much simpler than what you're describing Scruples. :) Nice to have a shortcut to it, as well as Texture Border Edges when doing UVs. (Oh and for selecting border edges, double clicking on them does the same as using the "Select Using Constraints" method, much…
In Maya there is no distinction between edges in the 3D viewport and edges in the UV window, so it's normal that when you select an edge in the UV window, the shared edges from the model will also be selected. The fact that it's selecting 3 separate borders in your example looks fishy, like there's some funky modeling…