[gtk/gtk-3-24: 1/2] x11: Honor hotspot during drag cancel animation

[Christoph Reiter <creiter src gnome org>]

commit a3cff0add1dec4db3ddc0a3dff8f41ff9e205b63
Author: Robert Mader <robert mader posteo de>
Date:   Mon Dec 9 01:16:39 2019 +0100

    x11: Honor hotspot during drag cancel animation
    
    Otherwise the icon "jumps" to the cursor position with its top left when
    the animation starts.
    This is especially visible if the dragged item is big, like when dragging
    mails in Thunderbird.

 gdk/x11/gdkdnd-x11.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)
---
diff --git a/gdk/x11/gdkdnd-x11.c b/gdk/x11/gdkdnd-x11.c
index f335d502ce..e07fa10325 100644
--- a/gdk/x11/gdkdnd-x11.c
+++ b/gdk/x11/gdkdnd-x11.c
@@ -2613,8 +2613,10 @@ gdk_drag_anim_timeout (gpointer data)
 
   gdk_window_show (context->drag_window);
   gdk_window_move (context->drag_window,
-                   context->last_x + (context->start_x - context->last_x) * t,
-                   context->last_y + (context->start_y - context->last_y) * t);
+                   (context->last_x - context->hot_x) +
+                   (context->start_x - context->last_x) * t,
+                   (context->last_y - context->hot_y) +
+                   (context->start_y - context->last_y) * t);
   gdk_window_set_opacity (context->drag_window, 1.0 - f);
 
   return G_SOURCE_CONTINUE;