[gtk+] widget: Add default snapshot implementation

[Matthias Clasen <matthiasc src gnome org>]

commit 8761d4d6095d464873a4a592ff8224df0acce7b2
Author: Timm Bäder <mail baedert org>
Date:   Wed May 3 11:11:20 2017 +0200

    widget: Add default snapshot implementation
    
    gtk_widget_snapshot will snapshot the css box, the default snapshot
    vfunc now gtk_widget_snapshot_child's all child widgets.

 gtk/gtkwidget.c |    7 ++++++-
 1 files changed, 6 insertions(+), 1 deletions(-)
---
diff --git a/gtk/gtkwidget.c b/gtk/gtkwidget.c
index 39c5498..b3293b3 100644
--- a/gtk/gtkwidget.c
+++ b/gtk/gtkwidget.c
@@ -940,7 +940,12 @@ static void
 gtk_widget_real_snapshot (GtkWidget   *widget,
                           GtkSnapshot *snapshot)
 {
-  /* nothing to do here */
+  GtkWidget *child;
+
+  for (child = _gtk_widget_get_first_child (widget);
+       child != NULL;
+       child = _gtk_widget_get_next_sibling (child))
+    gtk_widget_snapshot_child (widget, child, snapshot);
 }
 
 static void