If your default browser is not Safari or Firefox, on startup, FlickrFan will launch one of those browsers to display the home page of the desktop website. This change note explains a feature, new in version 0.38, that makes it possible to turn off this feature.
1. Update FlickrFan to v0.38.
2. Visit the Advanced prefs page. The third item is the one you want. Screen shot.
3. Check the box, click on Submit.
Next time you launch OPML, the desktop website home page will open in the default browser, OmniWeb, Opera, Camino, etc. (Even Firefox or Safari, for that matter.)
Eventually, if everything goes well, we'll phase out the feature. Didn't want to do it all at once because it's a dangerous place for breakage. One step at a time. 
