Hi Volker,
> I'am using WinTeXmacs and Maxima-5.9.3 on Windows.
>
> My session looks like this:
>
> (%I1) 'foo;
> (%O1) FOO
> (%I2) 'Foo;
> (%O2) Foo
> (%I3) 'FOO;
> (%O3) foo
> (%I4) %O3;
> (%O4) %o3
> (%I5) %o3;
> (%O5) foo
OK, when I try this with 5.9.3, command line and Xmaxima,
on Windows, I see stuff in the appropriate case.
So I believe the behavior you are seeing is a problem in TeXmacs.
Probably you should direct an inquiry to their mailing list.
Sorry I can't be more helpful,
Robert Dodier