[gtk: 1/7] x11 drag: Fix mapped error

[Matthias Clasen <matthiasc src gnome org>]

commit e702d425975a603f9e73f7de222406d9b5969a50
Author: Alexander Larsson <alexl redhat com>
Date:   Thu May 14 09:42:53 2020 +0200

    x11 drag: Fix mapped error
    
    In the gtk-demo drag-and-drop demo i can't drag anything, all I get
    is:
    
    (gtk4-demo:358993): Gdk-CRITICAL **: 09:36:19.617: Surface 0x7e1bb0 has not been mapped in 
GdkSeatGrabPrepareFunc
    
    This is because GdkX11Drag.ipc_surface is not considered mapped, even
    though we called gdk_x11_surface_show() on it, because the
    GDK_SURFACE_STATE_WITHDRAWN flag is still set.
    
    I added calls to gdk_synthesize_surface_state() to match what
    e.g. show_popup() and gdk_x11_toplevel_present() does.

 gdk/x11/gdkdrag-x11.c | 2 ++
 1 file changed, 2 insertions(+)
---
diff --git a/gdk/x11/gdkdrag-x11.c b/gdk/x11/gdkdrag-x11.c
index 3ae250c965..61160f9406 100644
--- a/gdk/x11/gdkdrag-x11.c
+++ b/gdk/x11/gdkdrag-x11.c
@@ -2028,6 +2028,8 @@ _gdk_x11_surface_drag_begin (GdkSurface         *surface,
   x11_drag->ipc_surface = ipc_surface;
   if (gdk_x11_surface_get_group (surface))
     gdk_x11_surface_set_group (x11_drag->ipc_surface, surface);
+
+  gdk_synthesize_surface_state (x11_drag->ipc_surface, GDK_SURFACE_STATE_WITHDRAWN, 0);
   gdk_x11_surface_show (x11_drag->ipc_surface, FALSE);
 
   x11_drag->drag_surface = create_drag_surface (display);