[gtk/misc-multiselection] singleselection: Clarify docs

[Matthias Clasen <matthiasc src gnome org>]

commit e72c243acab7eab57c98f05c93adb8f69e727281
Author: Matthias Clasen <mclasen redhat com>
Date:   Sat Jun 6 11:53:33 2020 -0400

    singleselection: Clarify docs
    
    Mention persistence and sorting.

 gtk/gtksingleselection.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)
---
diff --git a/gtk/gtksingleselection.c b/gtk/gtksingleselection.c
index 63db37d0de..5d0172c7b1 100644
--- a/gtk/gtksingleselection.c
+++ b/gtk/gtksingleselection.c
@@ -30,9 +30,14 @@
  * @Title: GtkSingleSelection
  * @see_also: #GtkSelectionModel
  *
- * GtkSingleSelection is an implementation of the #GtkSelectionModel interface 
+ * GtkSingleSelection is an implementation of the #GtkSelectionModel interface
  * that allows selecting a single element. It is the default selection method
  * used by list widgets in GTK.
+ *
+ * Note that the selection is *persistent* -- if the selected item is removed
+ * and re-added in the same ::items-changed emission, it stays selected. In
+ * particular, this means that changing the sort order of an underlying sort
+ * model will preserve the selection.
  */
 struct _GtkSingleSelection
 {