void BtnDail_Click(object sender, EventArgs e) { if (Lync.winDial == null) { WinDail dial = new WinDail(Lync); Lync.winDial = dial; dial.Show(); } else { IntPtr hwnd = new WindowInteropHelper(Lync.winDial).Handle; ShowWindow(hwnd, 1);//显示窗体 } }