WPF 激活现有窗口并关闭新窗口。

//关闭当前程序，显示已打开程序

private void App_Startup( object sender, StartupEventArgs e )
 {
    var current_process = Process.GetCurrentProcess( );
    var other_process = Process.GetProcessesByName( current_process.ProcessName ).FirstOrDefault( p => p.Id != current_process.Id );
    
    if( other_process != null && other_process.MainWindowHandle != IntPtr.Zero )
    {
       if( IsIconic( other_process.MainWindowHandle ) )
       {
          ShowWindow( other_process.MainWindowHandle, SW_RESTORE );
       }
       SetForegroundWindow( other_process.MainWindowHandle );
       Shutdown( );
    }
 }
   //是否窗口最小化 
 [DllImport( "user32" )]
 static extern bool IsIconic( IntPtr hWnd );
    //显示窗口
 [DllImport( "user32" )]
 static extern bool ShowWindow( IntPtr hWnd, int cmdShow );
 const int SW_RESTORE = 9;
    //将窗口显示在最前面
 [DllImport( "user32" )]
 static extern bool SetForegroundWindow( IntPtr hWnd );