[gtk+/gtk-3-22] gtkdnd: restore drag window movement for the unmanaged case

[Christoph Reiter <creiter src gnome org>]

commit 4496c5388b913db9288563618f69d35ae8dbf5b6
Author: Christoph Reiter <creiter src gnome org>
Date:   Wed Apr 26 12:46:40 2017 +0200

    gtkdnd: restore drag window movement for the unmanaged case
    
    5bb12474d975ee4b790c5 removed the dnd window movement code to let
    the gdk backends handle the window movement instead. While this
    works for X11/wayland the win32 backend still uses the unmanaged
    interface and expects the window movement to be handled on the gtk
    side. This restores the functionality in case the dnd is unmanaged.
    
    This fixes the drag window on Windows being stuck in the top left
    corner instead of following the drag position.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=781737

 gtk/gtkdnd.c |   43 ++++++++++++++++++++++++++++++++++---------
 1 files changed, 34 insertions(+), 9 deletions(-)
---
diff --git a/gtk/gtkdnd.c b/gtk/gtkdnd.c
index 2ed9b78..733909e 100644
--- a/gtk/gtkdnd.c
+++ b/gtk/gtkdnd.c
@@ -1674,6 +1674,20 @@ gtk_drag_dest_drop (GtkWidget      *widget,
  * Source side *
  ***************/
 
+
+static gboolean
+gtk_drag_is_managed (GtkWidget *source_widget)
+{
+  return
+#ifdef GDK_WINDOWING_X11
+    GDK_IS_X11_DISPLAY (gtk_widget_get_display (source_widget)) ||
+#endif
+#ifdef GDK_WINDOWING_WAYLAND
+    GDK_IS_WAYLAND_DISPLAY (gtk_widget_get_display (source_widget)) ||
+#endif
+    FALSE;
+}
+
 /* Like gtk_drag_begin(), but also takes a GtkIconHelper
  * so that we can set the icon from the source site information
  */
@@ -1699,16 +1713,9 @@ gtk_drag_begin_internal (GtkWidget          *widget,
   GdkWindow *ipc_window;
   gint start_x, start_y;
   GdkAtom selection;
-  gboolean managed = FALSE;
+  gboolean managed;
 
-  managed =
-#ifdef GDK_WINDOWING_X11
-    GDK_IS_X11_DISPLAY (gtk_widget_get_display (widget)) ||
-#endif
-#ifdef GDK_WINDOWING_WAYLAND
-    GDK_IS_WAYLAND_DISPLAY (gtk_widget_get_display (widget)) ||
-#endif
-    FALSE;
+  managed = gtk_drag_is_managed (widget);
 
   pointer = keyboard = NULL;
   ipc_widget = gtk_drag_get_ipc_widget (widget);
@@ -2020,6 +2027,22 @@ icon_widget_destroyed (GtkWidget         *widget,
 }
 
 static void
+gtk_drag_update_icon_window (GtkDragSourceInfo *info)
+{
+  if (!gtk_drag_is_managed (info->widget) && info->icon_window)
+    {
+      gtk_window_move (GTK_WINDOW (info->icon_window),
+                       info->cur_x - info->hot_x,
+                       info->cur_y - info->hot_y);
+
+      if (gtk_widget_get_visible (info->icon_window))
+        gdk_window_raise (gtk_widget_get_window (info->icon_window));
+      else
+        gtk_widget_show (info->icon_window);
+    }
+}
+
+static void
 gtk_drag_set_icon_widget_internal (GdkDragContext *context,
                                    GtkWidget      *widget,
                                    gint            hot_x,
@@ -2093,6 +2116,7 @@ gtk_drag_set_icon_widget_internal (GdkDragContext *context,
 
 out:
   gtk_drag_update_cursor (info);
+  gtk_drag_update_icon_window (info);
 }
 
 /**
@@ -2815,6 +2839,7 @@ gtk_drag_update_idle (gpointer data)
                                   info->possible_actions,
                                   &action, &possible_actions);
 
+      gtk_drag_update_icon_window (info);
       gdk_drag_find_window_for_screen (info->context,
                                        info->icon_window ? gtk_widget_get_window (info->icon_window) : NULL,
                                        info->cur_screen, info->cur_x, info->cur_y,