Add GtkSymbolicColor.

This is a small boxed struct used to store symbolic colors so they
can be resolved at a later point.

gtk/gtksymboliccolor.h

@@ -0,0 +1,49 @@
+/* GTK - The GIMP Toolkit
+ * Copyright (C) 2010 Carlos Garnacho <carlosg@gnome.org>
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 02111-1307, USA.
+ */
+
+#ifndef __GTK_SYMBOLIC_COLOR_H__
+#define __GTK_SYMBOLIC_COLOR_H__
+
+#include <gdk.h>
+//#include "gtkstyleset.h"
+
+G_BEGIN_DECLS
+
+/* Dummy typedefs */
+typedef struct GtkSymbolicColor GtkSymbolicColor;
+typedef struct GtkSymbolicColorMap GtkSymbolicColorMap;
+
+#define GTK_TYPE_SYMBOLIC_COLOR (gtk_symbolic_color_get_type ())
+
+GType gtk_symbolic_color_get_type (void) G_GNUC_CONST;
+
+GtkSymbolicColor * gtk_symbolic_color_new_literal (GdkColor         *color);
+GtkSymbolicColor * gtk_symbolic_color_new_name    (const gchar      *name);
+GtkSymbolicColor * gtk_symbolic_color_new_shade   (GtkSymbolicColor *color,
+                                                   gdouble           factor);
+GtkSymbolicColor * gtk_symbolic_color_new_mix     (GtkSymbolicColor *color1,
+                                                   GtkSymbolicColor *color2,
+                                                   gdouble           factor);
+
+GtkSymbolicColor * gtk_symbolic_color_ref   (GtkSymbolicColor *color);
+void               gtk_symbolic_color_unref (GtkSymbolicColor *color);
+
+G_END_DECLS
+
+#endif /* __GTK_SYMBOLIC_COLOR_H__ */