font selector: I had got the row and column counts in
gtk_table_new() back to front, so the space on the right was the
padding around five empty table columns! (And apparently a GtkTable
silently expands if you try to use rows that don't exist, which is
why I hadn't already noticed.)
Fixed that, and added some padding around the entire table. I think
my font selector is now finished, except for any bug fixes that come
up in testing.
[originally from svn r7954]