procedure TForm2.StatusBar1Click(Sender: TObject);
var
  mpt: TPoint;
  x: integer;
  j: integer;
  panel: integer;
begin
  if (StatusBar1.SimplePanel) OR (StatusBar1.Panels.Count = 0) then
  begin
    Memo1.Lines.Add('Clicked on a StatusBar, no Panels');
    Exit;
  end;

  mpt := Mouse.CursorPos;
  mpt := StatusBar1.ScreenToClient(mpt);
  panel := -1;
  x := 0;
  for j := 0 to StatusBar1.Panels.Count - 1 do
  begin
    x := x + StatusBar1.Panels[j].Width;
    if mpt.x < x then
    begin
      panel := j;
      Break;
    end;
  end;

  if panel = -1 then
    panel := -1 + StatusBar1.Panels.Count;

  Memo1.Lines.Add(Format('Clicked on StatusPanel %d', [panel]));
end;