Tonight, the Beta 9 improves the way walls are cut by a non rectangular door or window: a 3D shape is also added in the thickness of the wall around the cut out shape.
The following images show you the difference between beta 8 and beta 9:



This will make a difference only on a few 3D models, but will also let you export correct cut walls to OBJ format.

I also programmed an additional check on images when they are used as textures, to ensure that the images which contain a transparent color in their colors table, won't be misinterpreted as transparent textures when they actually don't use this transparent color. This should help to fight against transparency Z-buffer bug that we can see from time to time, and avoid reediting these falsely transparent images.