MenuStrip(主菜單)、ContextMenuStrip(右鍵菜單)的即時狀态的擷取方法

private void mi_Edit_DropDownOpened(object sender, EventArgs e)
        {
            mi_Edit_Undo.Enabled = textBox1.CanUndo;

            mi_Edit_Copy.Enabled = textBox1.SelectionLength > 0;
            mi_Edit_Cut.Enabled = mi_Copy.Enabled;

            mi_Edit_Paste.Enabled = Clipboard.ContainsText();
        }      

private void contextMenuStrip1_Opened(object sender, EventArgs e)
        {
            mi_Edit_Undo.Enabled = textBox1.CanUndo;

            mi_Copy.Enabled = textBox1.SelectionLength > 0;
            mi_Cut.Enabled = mi_Copy.Enabled;

            mi_Paste.Enabled = Clipboard.ContainsText();
        }