vb 窗体拖动

代码如下:
Option Explicit
Private Const WM_NCLBUTTONDOWN = &HA1
Private Const HTLEFT = 10
Private Const HTRIGHT = 11
Private Const HTTOP = 12
Private Const HTBOTTOM = 15
Private Const HTBOTTOMRIGHT = 17
Private Const HTBOTTOMLEFT = 16
Private Const HTTOPLEFT = 13
Private Const HTTOPRIGHT = 14

'sendmessage函数声明
Private Declare Function SendMessage Lib "user32" Alias "SendMessageA" (ByVal hwnd As Long, ByVal wMsg As Long, ByVal wParam As Long, lParam As Any) As Long
Private Declare Function ReleaseCapture Lib "user32" () As Long
Private Declare Function SetCapture Lib "user32" (ByVal hwnd As Long) As Long

Private intEdge As Integer '临界距离，鼠标在离边框距离小于等于该值则判定在边框上……

Private Sub Form_Load()
'相当于三个象素
intEdge