[metacity] window: add meta_window_get_toplevel_xvisual

[Alberts Muktupāvels <muktupavels src gnome org>]

commit 69f3e047d9a546a413f696468f5c99ba3e7d3017
Author: Alberts Muktupāvels <alberts muktupavels gmail com>
Date:   Fri Oct 4 19:55:19 2019 +0300

    window: add meta_window_get_toplevel_xvisual

 src/core/window.c    | 9 +++++++++
 src/include/window.h | 1 +
 2 files changed, 10 insertions(+)
---
diff --git a/src/core/window.c b/src/core/window.c
index efe58755..b7c6bfa0 100644
--- a/src/core/window.c
+++ b/src/core/window.c
@@ -8980,6 +8980,15 @@ meta_window_get_toplevel_xwindow (MetaWindow *window)
   return window->xwindow;
 }
 
+Visual *
+meta_window_get_toplevel_xvisual (MetaWindow *window)
+{
+  if (window->frame != NULL)
+    return meta_frame_get_xvisual (window->frame);
+
+  return window->xvisual;
+}
+
 /**
  * meta_window_get_transient_for:
  * @window: a #MetaWindow
diff --git a/src/include/window.h b/src/include/window.h
index 217ab4ba..c4837b92 100644
--- a/src/include/window.h
+++ b/src/include/window.h
@@ -39,6 +39,7 @@ MetaScreen *meta_window_get_screen (MetaWindow *window);
 MetaDisplay *meta_window_get_display (MetaWindow *window);
 Window meta_window_get_xwindow (MetaWindow *window);
 Window meta_window_get_toplevel_xwindow (MetaWindow *window);
+Visual *meta_window_get_toplevel_xvisual (MetaWindow *window);
 MetaWindow *meta_window_get_transient_for (MetaWindow *window);
 gboolean meta_window_is_fullscreen (MetaWindow *window);
 gboolean meta_window_is_maximized (MetaWindow *window);