[metacity] compositor-xrender: create root buffer in pre_paint

[Alberts Muktupāvels <muktupavels src gnome org>]

commit ffd3cc2d23522c5d905c83b46795e14b38adfe87
Author: Alberts Muktupāvels <alberts muktupavels gmail com>
Date:   Fri Oct 18 23:43:25 2019 +0300

    compositor-xrender: create root buffer in pre_paint

 src/compositor/meta-compositor-xrender.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)
---
diff --git a/src/compositor/meta-compositor-xrender.c b/src/compositor/meta-compositor-xrender.c
index 9cde995a..577b04c5 100644
--- a/src/compositor/meta-compositor-xrender.c
+++ b/src/compositor/meta-compositor-xrender.c
@@ -1169,9 +1169,6 @@ paint_all (MetaCompositorXRender *xrender,
       usleep (100 * 1000);
     }
 
-  if (xrender->root_buffer == None)
-    xrender->root_buffer = create_root_buffer (xrender);
-
   stack = meta_compositor_get_stack (META_COMPOSITOR (xrender));
   paint_windows (xrender, stack, xrender->root_buffer, region);
 
@@ -1816,6 +1813,9 @@ meta_compositor_xrender_pre_paint (MetaCompositor *compositor)
 
   xrender = META_COMPOSITOR_XRENDER (compositor);
 
+  if (xrender->root_buffer == None)
+    xrender->root_buffer = create_root_buffer (xrender);
+
   stack = meta_compositor_get_stack (compositor);
 
   for (l = stack; l != NULL; l = l->next)