C# 实现拖动控件

const uint WM_SYSCOMMAND = 0x0112;const uint SC_MOVE = 0xF010;const uint HTCAPTION = 0x0002;[DllImport("user32.dll",   EntryPoint="SendMessageA")]  private static extern int SendMessage(IntPtr hwnd, uint wMsg, uint wParam, uint lParam);  [DllImport("user32.dll")]  private static extern int ReleaseCapture();   void PictureBox1MouseDown(object sender, MouseEventArgs e){    ReleaseCapture();    SendMessage((sender as Control).Handle, WM_SYSCOMMAND, SC_MOVE + HTCAPTION, 0);}