void v_PropertyChanged(object sender, PropertyChangedEventArgs e)
{
RichTextBox rtb = sender as RichTextBox;
if (rtb.Tag != null)
{
ToolboxItem item = rtb.Tag as ToolboxItem;
Binding b = new Binding();
b.Source = this.Forcground;
item.SetBinding(ToolboxItem.ItemForegroundProperty, b);
}
}