Screen.PreviousControl的使用技巧

下面的示例将显示一条消息，如果上次获得焦点的控件不是txtFinalEntry文本框。

Public Function ProcessData() As Integer 

 ' No previous control error. 
 Const conNoPreviousControl = 2483 
 Dim ctlPrevious As Control 

 On Error GoTo Process_Err 

 Set ctlPrevious = Screen.PreviousControl 
 If ctlPrevious.Name = "txtFinalEntry" Then 
 ' 
 ' Process Data Here. 
 ' 
 ProcessData = True 
 Else 
 ' Set focus to txtFinalEntry and display message. 
 Me!txtFinalEntry.SetFocus 
 MsgBox "Please enter a value here." 
 ProcessData = False 
 End If 

Process_Exit: 
 Set ctlPrevious = Nothing 
 Exit Function 

Process_Err: 
 If Err = conNoPreviousControl Then 
 Me!txtFinalEntry.SetFocus 
 MsgBox "Please enter a value to process.", vbInformation 
 ProcessData = False 
 End If 
 Resume Process_Exit 

End Function