Reality Factory

If you go to customize template and change the Z sizes to 8 when the wall size is still, say, 16, you get a 'Brush_Clone > Brush == NULL' dialogue and then the program shuts down loosing your work.

Can be frustrating if you forget to change the wall thickness first.

RF Edit Pro version 0.7

Yep, that does happen. If you are making the z that small, then you probably want a solid brush? Make sure you change it to a solid brush before setting the size.