GTK Radiant Not Working Wright

[Leo Hibliss]

Hey guys I have a few questions and hope that you can help me. First off let me tell you that I am a modder for knights of the old republic and would like to move to jedi academy. I found this program that allows you to create maps GTK Radient I think if the name. Here's the thing after creating a room and moving inside it all sides woun't show the defalt texture. It give me a sigle thin and I mean thin line across the side. I have found no way to fix that and it has become a real pain to deal with. I had though it was a bad installation but so far no good.Anyone help me with this. If i can't fix it is there a different program that allows you to creat maps?