Now, I'm most probably walking on old ground here but i just found out a little trick in the DTE (Deep Terrain Editor). When you click the 'M' to go into the DTE, once there and you see all the information regarding the DTE, Shift click (Mouse click) the texture library (Top right pointing arrow from the main edit drop down list) and instead of getting the drop down list in text you get the whole textures pictures in view like you would selecting it from the texture library in Edit.

Smile, your dead a long time :)