HIG API for GTKMessageDialog, Take 4

[Carlos Garnacho <carlosg gnome org>]

Hi all,

Sorry for the delay, I've had only the essential time for hacking until
a few days ago. Now my work [1] matches with Matthias' suggestions [2],
but there are still a couple of issues:

- While I think that format_secondary_[text|markup]() is the correct
term, it's now discordant with the gtk_message_dialog_set_markup()
function, maybe we'd need a _format_markup() function?

- HIG also talks about authentication alert dialogs, but a little
addition must be done to gtkstock.c for being able to use this icon:

   ...
   { GTK_STOCK_DIALOG_ERROR, N_("Error"), 0, 0, GETTEXT_PACKAGE },
   { GTK_STOCK_DIALOG_QUESTION, N_("Question"), 0, 0, GETTEXT_PACKAGE },
+  { GTK_STOCK_DIALOG_AUTHENTICATION, N_("Authentication"), 0, 0, GETTEXT_PACKAGE },
   ...

- I'd also like to support the addition of a _set_widget() function,
nautilus already adds a GtkExpander in some dialogs, and it would be
useful too in auth dialogs or in any kind of input dialog.

	Carlos


[1] http://www.gnome.org/~carlosg/stuff/gtkmessagedialog/
[2] http://people.redhat.com/mclasen/higdialog/comparison.html