Procedure SetLBHorExtent(lb: TListBox);
  Var
    J, aMax: Integer;
    TempStr: String;
    aSize: TSize;
    MaxSize: Integer;
  Begin
    aMax := lb.Items.Count - 1;
    If aMax = -1 Then Exit;
    MaxSize := 0;
    For J := 0 To aMax Do
    Begin
      TempStr := lb.Items[J];
      Win32Check(GetTextExtentPoint32(Canvas.Handle, PChar(TempStr), Length(TempStr), aSize));
      If aSize.cx > MaxSize Then
        MaxSize := aSize.cx;
    End;
    If MaxSize = 0 Then Exit;
    Inc(MaxSize, 8);
    SendMessage(lb.Handle, LB_SETHORIZONTALEXTENT, MaxSize, 0);
  End;