Terrain Splatprototypes - Trouble changing textures through external GUI.

Hello, i have been working on some terrain functionality and i have been trying to write an editor to get quick access to "Add Terrain Texture" and "Edit Terrain Texture".

i have been following this article http://answers.unity3d.com/questions/351857/programatically-changing-the-tilesize-of-a-splatpr.html however can't seem to get the terrain to change textures in 5.2.3.

this is my code so far.

 void EditMenu(int i)
     {
         SplatPrototype splatMapData = t.terrainData.splatPrototypes [i];
         SplatPrototype newSplatMap = new SplatPrototype();
 
         Rect ProgressBox;
 
         int spacing = 3;
         float s = 120;
 
         Rect r;
 
         newSplatMap.texture = splatMapData.texture;
         newSplatMap.normalMap = splatMapData.normalMap;
         newSplatMap.tileOffset = splatMapData.tileOffset;
         newSplatMap.tileSize = splatMapData.tileSize;
 
         GUILayout.BeginVertical("box");
         
             GUILayout.BeginHorizontal ("label");
                 // diffuse texture
                 ProgressBox = EditorGUILayout.BeginVertical(GUILayout.MaxWidth(s));
                     r = new Rect(ProgressBox.x + spacing, ProgressBox.y + spacing, ProgressBox.width - spacing*2, ProgressBox.width - spacing*2);
 
                     newSplatMap.texture = (Texture2D) EditorGUI.ObjectField(r, newSplatMap.texture, typeof(Texture2D), true);
                     GUILayout.Space(s);
                 EditorGUILayout.EndVertical();
 
                 // normal texture
                 ProgressBox = EditorGUILayout.BeginVertical(GUILayout.MaxWidth(s));
                     r = new Rect(ProgressBox.x + spacing, ProgressBox.y + spacing, ProgressBox.width - spacing*2, ProgressBox.width - spacing*2);
 
                     newSplatMap.normalMap = (Texture2D) EditorGUI.ObjectField(r, newSplatMap.normalMap, typeof(Texture2D), true);
                     GUILayout.Space(s);
                 EditorGUILayout.EndVertical();
             GUILayout.EndHorizontal ();
 
             // offset
             newSplatMap.tileOffset = EditorGUILayout.Vector2Field("Tile Offset:", newSplatMap.tileOffset);
 
             // scale
             newSplatMap.tileSize = EditorGUILayout.Vector2Field("Tile Offset:", newSplatMap.tileSize);
 
             //end button
             if(GUILayout.Button("Done",GUILayout.Height (16)))
             {
                 myScript.SplatMapConstraints [i].editTexture = !myScript.SplatMapConstraints [i].editTexture ;
             }
 
         GUILayout.EndVertical();
 
         Debug.Log(newSplatMap.texture.name);
 
         t.terrainData.splatPrototypes [i] = newSplatMap;
 
         t.terrainData.RefreshPrototypes();
         t.Flush();
     }

it runs, however the values snap back. this function sits in a for loop to go through the texture and t = terrain

Is there anything i am missing or is there a way to open "Add Terrain Texture" and "Edit Terrain Texture" menus through code so i don't have to make my own. thank you for your help.