[gtk/x11-dnd-fixes: 2/3] x11: Fix dnd coordinate handling

[Matthias Clasen <matthiasc src gnome org>]

commit 7c1cfc5533d68655b001936168d8a5c2a6f7622b
Author: Matthias Clasen <mclasen redhat com>
Date:   Sat Feb 22 18:44:55 2020 -0500

    x11: Fix dnd coordinate handling
    
    We were not properly converting the coordinates we
    got to root coordinates. This was showing up as offsets
    between the actual drop target and the area where drops
    can happen, e.g. when dragging over a stack switcher
    to switch pages.

 gdk/x11/gdkdrag-x11.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)
---
diff --git a/gdk/x11/gdkdrag-x11.c b/gdk/x11/gdkdrag-x11.c
index c2bd36682a..04fa753fa3 100644
--- a/gdk/x11/gdkdrag-x11.c
+++ b/gdk/x11/gdkdrag-x11.c
@@ -2073,8 +2073,12 @@ _gdk_x11_surface_drag_begin (GdkSurface         *surface,
   precache_target_list (drag);
 
   gdk_device_get_position (device, &px, &py);
-  x_root = round (px) + dx;
-  y_root = round (py) + dy;
+
+  gdk_x11_surface_get_root_coords (surface,
+                                   round (px) + dx,
+                                   round (py) + dy,
+                                   &x_root,
+                                   &y_root);
 
   x11_drag->start_x = x_root;
   x11_drag->start_y = y_root;