thanks!

I know how to edit and import furniture libraries, but how do I delete the existing furniture library so that I can replace it with a new furniture library?

Many thanks to sjb007! He provided a working version.
It turned out that the problem was related to using "Import Furniture" and choosing a .zip file. When I extracted the zip and imported the .dae file, it worked just as it should.

perhaps easier to give you the window. I'll email it. (as soon as I figure out how to do that.)
but I think you're right about the furniture thing because when I double click on a regular window it gives me a small Modify Furniture dialogue box but when I double click on this one is gives me a large ...

The window is definitely tagged as a window (in addition to being put in the doors and windows category of the furniture list).
I enabled Magnetism.
The window does snap, but it snaps to the outside of the wall, not into the wall.

Windows that I imported (whether with Import Furniture or Import Furniture Library) will not snap into any wall.
I disabled magnetism.
Suggestions?
Thanks.

I want to do what the user guide instructed and make walls before clicking to create rooms. But if I make 4 walls of 20' each, the resulting room is not 20x20 but smaller. (How much smaller depends on the thickness of the wall.) Is there a formula I can use to create walls that will give a room that ...