Как перехватить событие кнопки biMaximize ?

if FOptions.Height <> 501 then
  FOptions.Height := 501
else
  FOptions.Height := 240;

unit Unit1;
 
interface
 
uses
  Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
  Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.StdCtrls;
 
type
  TForm1 = class(TForm)
  protected
    procedure WMSysCommand(var Msg: TWMSysCommand); message WM_SYSCOMMAND;
  end;
 
var
  Form1: TForm1;
 
implementation
 
{$R *.dfm}
 
procedure TForm1.WMSysCommand(var Msg: TWMSysCommand);
begin
  if Msg.CmdType = SC_MAXIMIZE then
  begin
    if Height <> 501 then Height:= 501
    else Height := 240;
  end else inherited;
end;
 
end.

procedure TForm1.WMSysCommand(var Msg: TWMSysCommand);
begin
  if Msg.CmdType = SC_MAXIMIZE then
  begin
    Memo1.Lines.Add('Maximize, ' + IntToStr(Random(100)));
  end else inherited;
end;

Procedure TForm1.WMSysCommand(Var Msg: TWMSysCommand);
Begin
If ((Msg.CmdType And $FFF0) = SC_MAXIMIZE) Then
  Begin
  Msg.Result := 0;
  If (Height < 500) Then
    Begin
    Height := 500;
    ShowMessage('A');
    End
  Else
    Begin
    Height := 240;
    ShowMessage('B');
    End;
  End
Else
  Inherited;
End;

var
  Check : integer = 0;
  Check2 : integer = 0;
 
procedure TForm1.WMSysCommand(var Msg: TWMSysCommand);
begin
  if Msg.CmdType = SC_MAXIMIZE then
    begin
      Inc(Check);
      Inc(Check2);
      if Odd(Check - round(Check2/2)) then
          Height:= 501
      else
          Height:= 240;
    end
  else inherited;
end;

var
  Check : integer = 0;
 
procedure TForm1.WMSysCommand(var Msg: TWMSysCommand);
begin
  if Msg.CmdType = SC_MAXIMIZE then
    begin
      Check:=(Check+1) mod 2;
      if Check = 0 then
          Height:= 501
      else
          Height:= 240;
    end
  else inherited;
end;

Procedure TForm1.WMSysCommand(Var Msg: TWMSysCommand);
Begin
If ((Msg.CmdType And $FFF0) = SC_MAXIMIZE) Then
  Begin
  Msg.Result := 0;
  If Odd(Tag) Then
    If (Height < 500) Then
      Begin
      Height := 500;
      // ShowMessage('A');
      End
    Else
      Begin
      Height := 240;
      // ShowMessage('B');
      End;
  Tag := Tag + 1;
  End
Else
  Inherited;
End;

procedure TForm1.FormCreate(Sender: TObject);
begin
  sSkinManager1.Active := False;
  sSkinManager1.Active := True;
end;