Is the 'key' property of meant to be used for anything?

The documentation suggests that it is an alternative for 'name' if non-null, but I can't seem to find anywhere in the source where the 'key' property is set or used.

Is it used by plugins, maybe?

Two things:

First, I realize that the link in my first post to the dormer images is broken. The correct link is https://www.sweethome3d.com/support/forum/viewthread_thread,11330_offset,240#61532

Second, I have uploaded my code to github. The patchset can be viewed at https://github.com/dkleszyk ...

Keet,

A wall, by definition, is usually a load baring part of the house. If the sides of a real dormer have a triangle gap at the bottom they are usually made of wood or another material that is not too heavy. A stone/concrete wall is too heavy for this type of construction. There is nothing to ...

I have been playing around with my local copy of sweethome3d to add support for walls with a sloping base.

I have found this much easier than creating invisible windows to cutout the base of the wall. The window technique can be seen in images 43/44 here https://www.sweethome3d.com/support/forum ...