tabs/font-lock/vc-hooks bad interaction
With a .emacs reduced to:
(require 'font-lock)
(require 'vc-hooks)
Do in a cvs-checkout'ed directory (xemacs/src for instance):
xemacs alloc.c
C-x 5 2
(in the new frame) C-x C-f dumper.c
In the new frame the active tab will still be on alloc.c.
OG.