MouseDown、MouseUp、MouseMove。VB 似乎提供了很好的 Mouse 事件。但好象还缺少什么！对！还差 MouseExit（鼠标移出）事件。在 VB 中，我们要捕捉 MouseExit 事件，必须用 API 函数：
Private Declare Function SetCapture Lib "user32" (ByVal hwnd As Long) As Long
Private Declare Function ReleaseCapture Lib "user32" () As Long
＇然后，我们可以在控件（以 Picture1 为例）的 MouseMove 事件上加上以下代码：
Dim MouseExit As Boolean
MouseOver = (0 <= x) And (x <= Picture1.Width) And (0 <= y) And (y <= Picture1.Height)
If MouseExit Then
＇........
SetCapture Picture1.hwnd
Else
＇........
ReleaseCapture
End If