不使用标题栏拖动窗口

摘自万一的博客：

1. 

WM_NCHITTEST

if msg.Result = HTCLIENT then
    msg.Result := HTCAPTION;
2.在wm_LbuttonDown 中

 ReleaseCapture;
  SendMessage(Handle, WM_SYSCOMMAND, $F011, 0);
  {参数3在 $F011-$F01F 之间均可都是移动控件}

3. sendmessage(this->GetSafeHandle, wm_nclbuttonDown, wparam, lparam);