方式一:
var rte = sender as RichTextEdit;
control = rte.Controls[] as RichEditControl;
方式二:
PropertyInfo myPropertyInfo1 = rte.GetType().GetProperty("InnerControl", BindingFlags.NonPublic | BindingFlags.Instance);
control = myPropertyInfo1.GetValue(gridView1.ActiveEditor as RichTextEdit, null) as RichEditControl;