Public Declare Function SendMessage Lib "user32" Alias _
"SendMessageA" (ByVal hWnd As Long, ByVal wMsg As Long, _
ByVal wParam As Long, lParam As Any) As Long
 
Public Const LVM_FIRST = &H1000
 
Public Sub AutoSize_Columns(LV As ListView, Optional Column As ColumnHeader = _
  Nothing)
  Dim C As ColumnHeader
  If Column Is Nothing Then
    For Each C In LV.ColumnHeaders
      SendMessage LV.hWnd, LVM_FIRST + 30, C.Index - 1, -1
    Next
  Else
    SendMessage LV.hWnd, LVM_FIRST + 30, Column.Index - 1, -1
  End If
  LV.Refresh
End Sub