[glade] Added missing prototype

[Juan Pablo Ugarte <jpu src gnome org>]

commit 2d05a15577df9ef1246e9ad48e44e97d340fc525
Author: Juan Pablo Ugarte <juanpablougarte gmail com>
Date:   Wed Oct 24 15:04:32 2012 -0700

    Added missing prototype

 gladeui/glade-design-private.h |    4 ++++
 1 files changed, 4 insertions(+), 0 deletions(-)
---
diff --git a/gladeui/glade-design-private.h b/gladeui/glade-design-private.h
index 3d14c06..a6babec 100644
--- a/gladeui/glade-design-private.h
+++ b/gladeui/glade-design-private.h
@@ -30,6 +30,10 @@ G_BEGIN_DECLS
 void _glade_design_view_freeze (GladeDesignView *view);
 void _glade_design_view_thaw   (GladeDesignView *view);
 
+void _glade_design_layout_get_colors (GtkStyleContext *context, 
+                                      GdkRGBA *c1, GdkRGBA *c2,
+                                      GdkRGBA *c3, GdkRGBA *c4);
+
 void _glade_design_layout_draw_node (cairo_t *cr,
                                      gdouble x,
                                      gdouble y,