Another information: I have a track in the ACTIVE LOG with 10000 trackpoints to use the TracBack function of the Vista HCx. If I need another track I have to delete or store this track. But it is not possible to store this track in the unit with 10000 trackpoints, the track will be shortened to 500 trackpoints and this is useless for me.

Therefore I create a transparent overlay of the track with all the 10000 trackpoints and merge it into my gmapsupp.img. This overlay I can activate or deactivate like any other map. To travel by bicycle this overlay is enough for me, the track is shown in a 2-pixel-line at the map and I can decide at every crossing or forking which way is the needed.

For tracks up to 500 trackpoints this is not neccessary, these tracks can be stored inside the unit and displayed in the map by default.

For reducing long tracks (up to 15000 trackpoints) there is a program here in the forum: http://forum.openstreetmap.org/viewtopic.php?id=7801

flux.