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;

Answer 2

If you put the button actually ON the page you want it to be visible on, then it will only appear when that page is visible. You have to set its location to be appropriate for that page and then set its Parent to the Parent of some other control already on that page.

Otherwise (if you want it to appear outside of the normal page area), do what Sertac said.