Another Strange Tile Issue

[Legacy_Pstemarie]

               This one has me stumped. Whenever we try painting a particular feature tile the tile leaves an imprint of itself across the area where ever you drag the mouse. When you finally place the tile, the imprints vanish leaving the painted tile in place just as if nothing funky had happened. Any ideas?
               
               

               
            

[Legacy_Rolo Kipp]

               <painting...>

Looks something like...


<...a picture>
               
               

               
            

[Legacy_Pstemarie]

               Nevermind - according to Six it has something to with how the toolset handles "additive textures"