bug#6505: make the Gtk+ port compile with -DGSEAL_ENABLE in preparation for Gtk+-3

[Chong Yidong]

Jan Djärv <jan.h.d@swipnet.se> writes:

> 25 jun 2010 kl. 23:42 skrev Dan Nicolaescu <dann@gnu.org>:
>
>> Good to hear you already have some solution.
>> IMHO the main thing is that emacs should not be seen as lagging
>> behind.  When the first distribution switches to version 3, it would be
>> good to have something available...
>
> I we must see a Gnome based on Gtk 3.0 first. It is not possible
> (without #ifdefs) to support < 2.14 and 3.0.
>
> If it is just a few ifdefs I will add them.  But we need to decide if
> configure should start to check for Gtk 3.0. Maybe now is the time.

Yes, I think bumping the requirement to 2.14 in the trunk is fine, as is
adding support for 3.0, provided it does not interfere with the GTK-2
support.  Thanks for working ahead on this.