Astrolabe, while certainly an excellent library that I don't want to denigrate at all, only provides some very basic world map icon handling. Basically, it just places an icon you create on the map at whatever X,Y coordinate is appropriate at the time, depending on which map is currently being viewed. It doesn't, however, move that icon or hide it as would be appropriate when you change which map you're viewing.
If you like, you could use the Astronomer library I wrote for my addons
ZoneDefense and
Intel, which adds some easy "fire-and-forget" functionality on top of Astrolabe (which it requires) to handle automatic adjustment of icon placement, size, visibility, alpha, etc. Please PM me if you decide to do that, as I like to get feedback from others that use my libraries.