Hi, I found a bug that probably causes the problems reported by Felx for Australia-Oceania: http://gis.19327.n5.nabble.com/SeaGenerator-in-overview2-branch-tp5761296p57... If the bounding box of a tile goes to 180.0 degrees (including), mkgmap saves the value 0x800000. This is interpreted as a negative value when the value is read back for the creation of the overview map. I've added a plausibility check to fix this, see attached patch. Maybe the better place for a correction would be in the write routine, but GPSMapEdit seems to have no problem with the value. @Steve: The same problem occurs in the display tool. Gerd