Hello, I have noticed that when I view a map in Mapsource, and I zoom out to a scale of 300 km or above, the entire map disappears. The problem is worse on Mac OS X using Garmin RoadTrip, as RoadTrip does not display tile boundaries. I found that adjusting the "topBits" attribute of OverviewMapDataSource.java changes this behaviour. If I set topBits = 11, the map can be displayed at scales of up to 1500 km. The comment in the code above this attribute, "// TODO need to change this.", seems to be a hint that this is not optimal. ;-) (Also, in my tests, if I lowered topBits to a value below 11, the entire map would not be displayed; with 11 the overview map is still not displayed at scale values of 2000 or 3000 km. Obviously a more comprehensive solution would be desirable.) - Is this a known issue? Is this restriction deliberate? I assume for this modification to be acceptable, the style files must be adjusted so as to not display excessive detail at these zoom levels. I have already done this in my custom style files: performance is reasonable. I am certainly not familiar with Java development in general, and definitely not with this project in particular, so I imagine that my modification will most likely not be suitable for general use. However, I have included the diff output below for your consideration anyway. Your comments would be appreciated. --- mkgmap-src/src/uk/me/parabola/mkgmap/reader/overview/ OverviewMapDataSource.java 2009-02-10 16:45:16.000000000 +0100 +++ mkgmap-trunk/src/uk/me/parabola/mkgmap/reader/overview/ OverviewMapDataSource.java 2009-02-21 18:04:15.000000000 +0100 @@ -45,7 +45,7 @@ // TODO need to change this. private final int topLevel = 5; - private final int topBits = 14; + private final int topBits = 11; /** * This is a fake source of data and is not read from a file, so always