vb一窗口拖动问题

Const HTCAPTION = 2
Const WM_NCLBUTTONDOWN = &HA1
Private Declare Function ReleaseCapture Lib "user32" () As Long
Private Declare Function SendMessage Lib "user32" Alias "SendMessageA" (ByVal hwnd As Long, ByVal wMsg As Long, ByVal wParam As Long, lParam As Long) As Long

Private Sub Form_MouseDown(Button As Integer, Shift As Integer, X As Single, Y As Single)
If Button = 1 Then '是否左键
Dim ReturnVal As Long
X = ReleaseCapture()
ReturnVal = SendMessage(hwnd, WM_NCLBUTTONDOWN, HTCAPTION, 0)
End If
End Sub

Form_MouseDown 中的 Form可以换成图片框。