Alexandre Julliard : user32: Don' t copy window bits to or from the dummy surface.

[Alexandre Julliard]

Module: wine
Branch: master
Commit: 3cd66cf7b17affe18d67ae7600349f3a22dd36d1
URL:    https://source.winehq.org/git/wine.git/?a=commit;h=3cd66cf7b17affe18d67ae7600349f3a22dd36d1

Author: Alexandre Julliard <julliard at winehq.org>
Date:   Wed Jul  4 16:07:34 2018 +0200

user32: Don't copy window bits to or from the dummy surface.

Signed-off-by: Alexandre Julliard <julliard at winehq.org>

---

 dlls/user32/winpos.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/dlls/user32/winpos.c b/dlls/user32/winpos.c
index c792b0e..659321c 100644
--- a/dlls/user32/winpos.c
+++ b/dlls/user32/winpos.c
@@ -2091,6 +2091,12 @@ BOOL set_window_pos( HWND hwnd, HWND insert_after, UINT swp_flags,
     old_client_rect = win->client_rect;
     old_surface = win->surface;
     if (old_surface != new_surface) swp_flags |= SWP_FRAMECHANGED;  /* force refreshing non-client area */
+    if (new_surface == &dummy_surface) swp_flags |= SWP_NOREDRAW;
+    else if (old_surface == &dummy_surface)
+    {
+        swp_flags |= SWP_NOCOPYBITS;
+        valid_rects = NULL;
+    }
 
     SERVER_START_REQ( set_window_pos )
     {