[gtk/wip/matthiasc/popup5: 14/15] Mention gtk_widget_get_toplevel in the migration guide.

[Matthias Clasen <matthiasc src gnome org>]

commit 7c5b2521a0837470a3888faf2c9a86f0ab6e271c
Author: Matthias Clasen <mclasen redhat com>
Date:   Mon May 20 04:52:22 2019 +0000

    Mention gtk_widget_get_toplevel in the migration guide.

 docs/reference/gtk/migrating-3to4.xml | 8 ++++++++
 1 file changed, 8 insertions(+)
---
diff --git a/docs/reference/gtk/migrating-3to4.xml b/docs/reference/gtk/migrating-3to4.xml
index 73f7a659b9..a1d9dd08b5 100644
--- a/docs/reference/gtk/migrating-3to4.xml
+++ b/docs/reference/gtk/migrating-3to4.xml
@@ -780,6 +780,14 @@
         Use GTK_IS_ROOT, GTK_IS_NATIVE or GTK_IS_WINDOW
         instead, as appropriate.
       </para>
+
+    <section>
+      <title>gtk_widget_get_toplevel has been removed</title>
+      <para>
+        gtk_widget_get_toplevel() has been removed.
+        Use gtk_widget_get_root() or gtk_widget_get_native()
+        instead, as appropriate.
+      </para>
   </section>
 
 </chapter>