[mkgmap-dev] garmin zumo XT

I was successfully building maps for a Montana with my own style. Since the Montana died, I replaced it with a Zumo XT.   It isn't working so well now.   I can use my map on qmapshack and it looks as expected, but on the Zumo it appears that Garmin does not recognize some (or all) my custom type codes.   Any ideas what the limitations are,  or how to work with this?   They've added something called 'Map Theme', which is a small xml file.   I don't see a way to load my typ file, but I didn't need to do that before since I included that with the mkgmap build. Brad