How can I made a button that is only visible at a specific page? (Inno Setup)

Question

I have made a button in the wizard pages. But I only want to show that button on this serial form page. Now, the button is showed at all wizard pages. How can I let it show only at the serial page?

This is the code that i have used for the serial form page:

[Code]
enter code here function SetFocus(hWnd: HWND): HWND;
  external 'SetFocus@user32.dll stdcall';
function OpenClipboard(hWndNewOwner: HWND): BOOL;
  external 'OpenClipboard@user32.dll stdcall';
function GetClipboardData(uFormat: UINT): THandle;
  external 'GetClipboardData@user32.dll stdcall';
function CloseClipboard: BOOL;
  external 'CloseClipboard@user32.dll stdcall';
function GlobalLock(hMem: THandle): PAnsiChar;
  external 'GlobalLock@kernel32.dll stdcall';
function GlobalUnlock(hMem: THandle): BOOL;
  external 'GlobalUnlock@kernel32.dll stdcall';

var
  SerialPage: TWizardPage;
  SerialEdits: array of TEdit;

const
  CF_TEXT = 1;
  VK_BACK = 8;
  SC_EDITCOUNT = 6;
  SC_CHARCOUNT = 5;

function GetClipboardText: string;
var
  Data: THandle;
begin
  Result := '';
  if OpenClipboard(0) then
  try
    Data := GetClipboardData(CF_TEXT);
    if Data <> 0 then
      Result := String(GlobalLock(Data));
  finally
    if Data <> 0 then
      GlobalUnlock(Data);
    CloseClipboard;
  end;
end;

function TryPasteSerialNumber: Boolean;
var  
  S: string;
  I: Integer;
  J: Integer;
  Delimiter: string;
begin
  Result := True;
  Delimiter := '-';
  S := GetClipboardText;    
  if Length(S) <> ((SC_EDITCOUNT * SC_CHARCOUNT) + 
    ((SC_EDITCOUNT - 1) * Length(Delimiter))) then
    Exit;    
  for I := 0 to GetArrayLength(SerialEdits) - 1 do
  begin
    J := (I * SC_CHARCOUNT) + (I * Length(Delimiter)) + 1;
    SerialEdits[I].Text := Copy(S, J, SC_CHARCOUNT);
  end;
end;

function GetSerialNumber(const ADelimiter: Char): string;
var
  I: Integer;
begin
  Result := '';
  for I := 0 to GetArrayLength(SerialEdits) - 1 do
    Result := Result + SerialEdits[I].Text + ADelimiter;
  Delete(Result, Length(Result), 1);
end;

procedure OnSerialEditChange(Sender: TObject);
var
  CanContinue: Boolean;
begin
  CanContinue := GetSerialNumber('-') = 'my serial';
  WizardForm.NextButton.Enabled := CanContinue;
end;

procedure OnSerialEditKeyDown(Sender: TObject; var Key: Word;
  Shift: TShiftState);
var
  Edit: TEdit;
  EditIndex: Integer;
begin
  Edit := TEdit(Sender);
  EditIndex := Edit.TabOrder - SerialEdits[0].TabOrder;
  if (EditIndex = 0) and (Key = Ord('V')) and (Shift = [ssCtrl]) then
  begin
    if TryPasteSerialNumber then
      Key := 0;
  end
  else
  if (Key >= 32) and (Key <= 255) then
  begin
    if Length(Edit.Text) = SC_CHARCOUNT - 1 then
    begin
      if EditIndex < GetArrayLength(SerialEdits) - 1 then
        SetFocus(SerialEdits[EditIndex + 1].Handle)
      else
        SetFocus(WizardForm.NextButton.Handle);
    end;
  end
  else
  if Key = VK_BACK then
    if (EditIndex > 0) and (Edit.Text = '') and (Edit.SelStart = 0) then
      SetFocus(SerialEdits[EditIndex - 1].Handle);
end;

procedure CreateSerialNumberPage;
var
  I: Integer;
  Edit: TEdit;
  DescLabel: TLabel;
  EditWidth: Integer;
begin
  SerialPage := CreateCustomPage(wpWelcome, 'Serial number validation',
    'Enter the valid serial number');

  DescLabel := TLabel.Create(SerialPage);
  DescLabel.Top := 16;
  DescLabel.Left := 0;
  DescLabel.Parent := SerialPage.Surface;
  DescLabel.Caption := 'Enter the valid serial number and continue with the installation...';
  DescLabel.Font.Style := [fsBold];

  SetArrayLength(SerialEdits, SC_EDITCOUNT);
  EditWidth := (SerialPage.SurfaceWidth - ((SC_EDITCOUNT - 1) * 8)) div SC_EDITCOUNT;

  for I := 0 to SC_EDITCOUNT - 1 do
  begin
    Edit := TEdit.Create(SerialPage);
    Edit.Top := 40;
    Edit.Left := I * (EditWidth + 8);
    Edit.Width := EditWidth;
    Edit.CharCase := ecUpperCase;
    Edit.MaxLength := SC_CHARCOUNT;
    Edit.Parent := SerialPage.Surface;
    Edit.OnChange := @OnSerialEditChange;
    Edit.OnKeyDown := @OnSerialEditKeyDown;
    SerialEdits[I] := Edit;
  end;
end;

procedure CurPageChanged(CurPageID: Integer);
begin
  if CurPageID = SerialPage.ID then
    WizardForm.NextButton.Enabled := False;  
end;

procedure AboutButtonOnClick(Sender: TObject);
var
  ErrorCode: Integer;
begin
  ShellExecAsOriginalUser('open', 'http://www.mywebsite.com', '', '', SW_SHOWNORMAL, ewNoWait, ErrorCode);
end;

procedure CreateAboutButton(ParentForm: TSetupForm; CancelButton: TNewButton);
var
  AboutButton: TNewButton;
begin
  AboutButton := TNewButton.Create(ParentForm);
  AboutButton.Left := ParentForm.ClientWidth - CancelButton.Left - CancelButton.Width;
  AboutButton.Top := CancelButton.Top;
  AboutButton.Width := CancelButton.Width;
  AboutButton.Height := CancelButton.Height;
  AboutButton.Caption := '&Get Serial';
  AboutButton.OnClick := @AboutButtonOnClick;
  AboutButton.Parent := ParentForm;
end;

procedure InitializeWizard;
begin
  CreateSerialNumberPage;
  CreateAboutButton(WizardForm, WizardForm.CancelButton);
end;

I hope you can help me guys!

Answer 1

You already have a CurPageChanged procedure, you can set visibility of your button here depending on the current page. Of course you need to make your 'AboutButton' a global var:

...

var
  AboutButton: TNewButton;

procedure CreateAboutButton(ParentForm: TSetupForm; CancelButton: TNewButton);
begin
  AboutButton := TNewButton.Create(ParentForm);
  ...
end;


procedure CurPageChanged(CurPageID: Integer);
begin
  ...
  AboutButton.Visible := CurPageID = SerialPage.ID;
end;