只要在splitimage_MouseDown內增加壹行代碼即可：
Private Sub splitimage_MouseDown(Index As Integer, Button As Integer, Shift As Integer, X As Single, Y As Single)
splitimage(Index).Print Index
If DoesControlExist(splitimage(splitx * splity)) Then
Unload splitimage(splitx * splity)
End If
Load splitimage(splitx * splity)
splitimage(splitx * splity) = splitimage(Index)
splitimage(splitx * splity).Visible = True
splitimage(Index).ZOrder (0) '新增的代碼！
End Sub