How can I tell which workbook triggered an event?

I have a BeforeClose event in a workbook, however if the user closes the workbook when it is not the active workbook, e.g. from the taskbar, the script executes on the wrong workbook.

Is there a way to tell which workbook triggered the event and reference that workbook rather than ActiveWorkbook?

Private Sub Workbook_BeforeClose(Cancel As Boolean)
'   Replaces default Save message box with custom one
'   that includes request stats, waings, and errors.
    If Not ActiveWorkbook.Saved Then
        UF_Stats.Show
        If Not GlobalVariables.bAllowClose Then Cancel = True
    End If
End Sub