I figured out how to get the program to show portages overlayed on the map by pointing to the file on Azelea's site:
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For some reason the campsite + portage gpx file doesn't seem to work though.  I think it may be the "+" in the file name that is confusing the app.  Perhaps it is something else though.

Anyway,  Gmap4 is a neat and useful app, thanks for pointing it out!