padding to class structures

[George <jirka 5z com>]

I was talking to anders and realized that we may want to add signals and/or
virtual methods in the future to widgets, and it'd be nice to do so without
breaking binary compatibility.  So the idea would be to add padding to all
the (non-deprecated) class structures in libgnome/libgnomeui for this.  This
doesn't take up much memory since there is only once class structure per
class so that's not an issue.

But it does break bin-compat a bit now.  Though looking at the schedule we
can still do this correct?  It would only break bincompat for people who
derive the widgets, so I don't think it'd even be such a problem.

If I don't hear back within a day or two, I'll commit it.

George

-- 
George <jirka 5z com>
   A clever man commits no minor blunders.
                       -- Goethe