[gtk+] docs: improve the documentation of GtkEntry:attributes

[Sébastien Wilmet <swilmet src gnome org>]

commit 88699f588d8e04696d04e6fdd1a73fd288521431
Author: Sébastien Wilmet <swilmet gnome org>
Date:   Fri Nov 25 20:08:00 2016 +0100

    docs: improve the documentation of GtkEntry:attributes
    
    See the implementation of gtk_entry_create_layout():
    pango_attr_list_splice() is used to add the PangoAttrList of the preedit
    string. And that is done *after* applying the PangoAttrList of the
    "attributes" property.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=776868

 gtk/gtkentry.c |    3 +++
 1 files changed, 3 insertions(+), 0 deletions(-)
---
diff --git a/gtk/gtkentry.c b/gtk/gtkentry.c
index 4bc0be2..2a04129 100644
--- a/gtk/gtkentry.c
+++ b/gtk/gtkentry.c
@@ -1378,6 +1378,9 @@ gtk_entry_class_init (GtkEntryClass *class)
    *
    * This is mainly useful to change the size or weight of the text.
    *
+   * The #PangoAttribute's @start_index and @end_index must refer to the
+   * #GtkEntryBuffer text, i.e. without the preedit string.
+   *
    * Since: 3.6
    */
   entry_props[PROP_ATTRIBUTES] =