In fact, the code for the world map in my viewer should work... and it does... after four missing lines are added in app_settings/message_template.msg (if only the OpenSim developers could
document the changes they make to the SL messaging protocol) !
You can grab
this updated/fixed message_template.msg and place it into the viewer installation app_setting/ sub-directory, replacing the old file. It will auto-magically fix the world map !
The mini-map is still partly broken however (the land tile is not properly centered for var regions). Still some work for me to do...