Hi All,
I just noticed that the 'Options->Terrain->Select texture...' menu option in Sapphire is broken, and probably has been since L3DT v2.9 dev build 1. I have fixed this option for the next update, which should be L3DT release 11.08.
Cheers,
Aaron.
PS: If you've never used this option, it allows you to overlay different maps in the project as the terrain texture in Sapphire. For instance, here is a rendering of the heightfield contour lines from the 2D view being overlaid as the texture: