private void pictureBox1_MouseMove(object sender, MouseEventArgs e)
{
if (e.Button == MouseButtons.Left)
{
((Control)sender).Capture = false;
const int WM_NCLBUTTONDOWN = 0xA1;
IntPtr HTCAPTION = (IntPtr)2;
Message msg = Message.Create(this.Handle, WM_NCLBUTTONDOWN, HTCAPTION, IntPtr.Zero);
this.DefWndProc(ref msg);
}
}