用VB倒是很容易实现，但是用WinCC就不懂了。

先引用API函数：
Private Declare Function ReleaseCapture Lib "user32" () As Long

在到控件的mousemove事件里面改变显示属性：
Private Sub Picture2_MouseMove(Button As Integer, Shift As Integer, X As Single, Y As Single)
Dim MouseOver As Boolean

MouseOver = (0 <= X) And (X <= Picture2.Width) And (0 <= Y) And (Y <= Picture2.Height)
If MouseOver Then
Picture2.Appearance = 1
SetCapture Picture2.hWnd
Else
Picture2.Appearance = 0
ReleaseCapture
End If
End Sub

那位高手转成WinCC可用的方法，呵呵.