[gtk/wip/otte/sortlistmodel2: 21/27] sortlistmodel: Make sort stable again

[Benjamin Otte <otte src gnome org>]

commit 7921e935f32f8269d4c1f9ca00ccdf9161164ae1
Author: Benjamin Otte <otte redhat com>
Date:   Tue Jul 21 04:06:13 2020 +0200

    sortlistmodel: Make sort stable again
    
    Previously, the sort was not stable when items were added/removed while
    sorting or the sort algorithm was changed.
    
    Now the sort looks at the item position (via the key's location in the
    keys array) to make sure each comparison stays stable with respect to
    this position.

 gtk/gtksortlistmodel.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)
---
diff --git a/gtk/gtksortlistmodel.c b/gtk/gtksortlistmodel.c
index 3b3e402191..72db0c05db 100644
--- a/gtk/gtksortlistmodel.c
+++ b/gtk/gtksortlistmodel.c
@@ -255,7 +255,11 @@ sort_func (gconstpointer a,
   gpointer *sb = (gpointer *) b;
   int result;
 
-  return gtk_sort_keys_compare (data, *sa, *sb);
+  result = gtk_sort_keys_compare (data, *sa, *sb);
+  if (result)
+    return result;
+
+  return *sa < *sb ? -1 : 1;
 }
 
 static gboolean