捕捉 MouseExit 事件   
       
MouseDown、MouseUp、MouseMove。VB 似乎提供了很好的 Mouse 事件。但好象還缺少什么！對！還差 MouseExit（鼠標移出）事件。在 VB 中，我們要捕捉 MouseExit 事件，必須用 API 函數：
Private Declare Function SetCapture Lib "user32" (ByVal hWnd As Long) As Long
Private Declare Function ReleaseCapture Lib "user32" () As Long
然后，我們可以在控件（以 Picture1 為例）的 MouseMove 事件上加上以下代碼：

With Picture1 'Change this to the name of the control
If Button = 0 Then
If (X < 0) Or (Y < 0) Or (X > .Width) Or (Y > .Height) Then
'Mouse pointer is outside button, so let other controls receive
'mouseevents too:
ReleaseCapture
' 放入鼠標離開的代碼
Else
' Mouse pointer is over button, so we'll capture it, thus
' we'll receive mouse messages even if the mouse pointer is
' not over the button
SetCapture .hwnd

' 放入鼠標進入的代碼
End If