First: Gnuite / JohnC, Maemo Mapper is incredible! Thanks for building it!

Can somebody explain how Maemo Mapper chooses the area which maps will be downloaded for? I'm trying to download maps for my home city and for cities I travel to.

The docs say that maps will be downloaded within a rectangle whose corners are where you clicked to center previously, and where you're currently centered.

I tried that, but the maps I end up with don't match up with the area I chose.

Can someone please explain the agorithm Maemo Mapper uses for this?