Comment 4 for bug 861351

I suggest a way to keep the code simpler could be to have #defines, starting like this:

#if !GTK_CHECK_VERSION(3,0,0)
    #define GTK_DIALOG_NO_SEPARATOR 0
    #define gtk_combo_box_text_get_active_text gtk_combo_box_append_text
    #define gtk_combo_box_text_append_text gtk_combo_box_append_text
    #define gtk_combo_box_text_new gtk_combo_box_new_text
    /* key defines go here */
#endif

As for WAF, Postler can serve as an example. If you want, I can also take care of fixing that up. http://git.xfce.org/apps/postler/tree/wscript#n119