It should be possible to force also "good old plain qt-programs" into portrait mode in N9:
http://harmattan-dev.nokia.com/docs/..._rotation.html
http://harmattan-dev.nokia.com/docs/...plain_Qt_Quick

Better yet, you should easily be able to make a dummy QML wrapper for the Qt code. Basically just a Page QML Harmattan element that contains the Qt view (QGraphicsView probably?).
Then just fix the orientation to always be portrait (above links clearly show how). Of course some of the Qt-code needs changing due to this but that should be no problem since you're using the symbian base of the codes which do already support portrait.

For me using landscape mode for a geocaching application is quite cumbersome if not impossible. Holding N9 in landscape mode with one hand is tricky to say at least. So supporting portrait should be the next step IMHO if you want ppl to use this app.

Oh, and thanks for re-enabling the "hide found/own caches"!

PS: The arrow that shows current position seems to point at random directions. At least it did that when I tried briefly in the field last time I was caching..