[gtk/gtk-3-24: 1/2] Gdk-Win32: Correct handling of transient state changes

[Matthias Clasen <matthiasc src gnome org>]

commit 6348a7d48ffb24f95b7fe8dd2cc29a7cd7e6de98
Author: Luca Bacci <luca bacci982 gmail com>
Date:   Tue Jul 17 12:01:54 2018 +0200

    Gdk-Win32: Correct handling of transient state changes
    
    gdk_win32_window_set_transient_for() behaves incorrectly when
    called in sequence with the same arguments. This fix ensures it
    always operates correctly.
    In some cases this function gets called multiple times with the
    same arguments, e.g. when tooltips are shown.
    
    See issue #1214

 gdk/win32/gdkwindow-win32.c | 38 +++++++++++++++++---------------------
 1 file changed, 17 insertions(+), 21 deletions(-)
---
diff --git a/gdk/win32/gdkwindow-win32.c b/gdk/win32/gdkwindow-win32.c
index 28f2b7696d..2b6733fb8f 100644
--- a/gdk/win32/gdkwindow-win32.c
+++ b/gdk/win32/gdkwindow-win32.c
@@ -1085,17 +1085,11 @@ gdk_win32_window_destroy (GdkWindow *window,
   _gdk_remove_modal_window (window);
 
   /* Remove all our transient children */
-  tmp = window_impl->transient_children;
-  while (tmp != NULL)
+  while (window_impl->transient_children != NULL)
     {
-      GdkWindow *child = tmp->data;
-      GdkWindowImplWin32 *child_impl = GDK_WINDOW_IMPL_WIN32 (GDK_WINDOW (child)->impl);
-
-      child_impl->transient_owner = NULL;
-      tmp = tmp->next;
+      GdkWindow *child = window_impl->transient_children->data;
+      gdk_window_set_transient_for (child, NULL);
     }
-  g_slist_free (window_impl->transient_children);
-  window_impl->transient_children = NULL;
 
 #ifdef GDK_WIN32_ENABLE_EGL
   display = GDK_WIN32_DISPLAY (gdk_window_get_display (window));
@@ -2127,27 +2121,29 @@ gdk_win32_window_set_transient_for (GdkWindow *window,
       return;
     }
 
-  if (parent == NULL)
+  if (window_impl->transient_owner == parent)
+    return;
+
+  if (GDK_IS_WINDOW (window_impl->transient_owner))
     {
       GdkWindowImplWin32 *trans_impl = GDK_WINDOW_IMPL_WIN32 (window_impl->transient_owner->impl);
-      if (trans_impl->transient_children != NULL)
-        {
-          item = g_slist_find (trans_impl->transient_children, window);
-          item->data = NULL;
-          trans_impl->transient_children = g_slist_delete_link (trans_impl->transient_children, item);
-          trans_impl->num_transients--;
+      item = g_slist_find (trans_impl->transient_children, window);
+      item->data = NULL;
+      trans_impl->transient_children = g_slist_delete_link (trans_impl->transient_children, item);
+      trans_impl->num_transients--;
 
-          if (!trans_impl->num_transients)
-            {
-              trans_impl->transient_children = NULL;
-            }
+      if (!trans_impl->num_transients)
+        {
+          trans_impl->transient_children = NULL;
         }
+
       g_object_unref (G_OBJECT (window_impl->transient_owner));
       g_object_unref (G_OBJECT (window));
 
       window_impl->transient_owner = NULL;
     }
-  else
+
+  if (parent)
     {
       parent_impl = GDK_WINDOW_IMPL_WIN32 (parent->impl);