函数：

Function ClearList(lst As ListBox) As Boolean
On Error GoTo Err_ClearList
    'Purpose:   Unselect all items in the listbox.
    'Return:    True if successful
    Dim varItem As Variant

    If lst.MultiSelect = 0 Then
        lst = Null
    Else
        For Each varItem In lst.ItemsSelected
            lst.Selected(varItem) = False
        Next
    End If

    ClearList = True

Exit_ClearList:
    Exit Function

Err_ClearList:
    Call LogError(Err.Number, Err.Description, "ClearList()")
    Resume Exit_ClearList
End Function

Public Function SelectAll(lst As ListBox) As Boolean
On Error GoTo Err_Handler
    'Purpose:   Select all items in the multi-select list box.
    'Return:    True if successful
    Dim lngRow As Long

    If lst.MultiSelect Then
        For lngRow = 0 To lst.ListCount - 1
            lst.Selected(lngRow) = True
        Next
        SelectAll = True
    End If

Exit_Handler:
    Exit Function

Err_Handler:
    Call LogError(Err.Number, Err.Description, "SelectAll()")
    Resume Exit_Handler
End Function