I agree with Jan Morales.
I am running Gnome desktop 2.8.0 under FC3 and have installed thunderbird-1.0.2 from the RPM that came across the yum updater.
I tried installing the linc-1.0.3-3.1.i386.rpm and did a touch .autoreg in /usr/lib/thunderbird-1.0.2 and also in /usr/bin to no avail.
I am also getting the gray background for the mail message text portion of the window.
Dave
I hate to say it but me too, I am running FC3, XFCE4.2 (compiled by myself) and have installed the linc rpm and touch'ed /usr/lib/thunderbird-1.0.2/.autoreg as root still no joy
as luck would have it I installed thunderbird 1.0 in /usr/local
so I have a fall-back... although I could get used to this grey background, much better for the eyes;-)
Martin