(Only If You want cool ).

It appears you don't want.
Why?:

I dunno, I'm just lazy, I guess [:p]

The package versions have always worked well in the past and I'm just used to doing dpkg for anything I want to install.

So: I finally got around to doing what you told me to do and installed SH3D 6.3 via the file from Sourceforge - and it fixed the problem. I now no longer have the option greyed out and I can view "Top View".

Some other time that's not so late at night, I'll carry on through the instructions for the library editors.

Many many thanks for your help.