If I start up xemacs, the font used is Lucidatypewriter 14. The
Options Menu the agrees with this, as indicated by the green diamonds.
The font was set using the following X resource:
Emacs.default.attributeFont: -*-Lucidatypewriter-Medium-R-*-*-*-120-*-*-*-*-*-*
If I then change the font SIZE from 14 to 18 using Options->Size->18,
the font size does indeed change, but the typeface changes from
Lucidatypewriter to Courier. I have to use
Options->Font->Lucidatypewriter to get back to my preferred typeface.
This seems like a clear user interface bug.
Although `custom' is involved here, this is not obvious to the
untrained observer.
Martin