Code:

program Test;

uses
  Forms,
  TestMainForm in 'TestMainForm.pas' {Form1},
  SplashScreen in 'SplashScreen.pas';

{$R *.res}

begin
  Application.Initialize;
  Application.CreateForm(TForm1, Form1);
  Application.Run;
end.

Code:

unit TestMainForm;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, SplashScreen, StdCtrls, ComCtrls;

type
  TForm1 = class(TForm)
    Button1: TButton;
    TrackBar1: TTrackBar;
    Label1: TLabel;
    Label2: TLabel;
    procedure Button1Click(Sender: TObject);
    procedure TrackBar1Change(Sender: TObject);
    procedure FormClose(Sender: TObject; var Action: TCloseAction);
    procedure FormCreate(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

type
  TUpdateLayeredWindow = function(Handle: THandle; hdcDest: HDC; pptDst:
    PPoint; _psize: PSize; hdcSrc: HDC; pptSrc: PPoint; crKey: COLORREF;
    pblend: PBLENDFUNCTION; dwFlags: DWORD): Boolean; stdcall;

var
  UpdateLayeredWindow: TUpdateLayeredWindow = nil;

procedure TForm1.Button1Click(Sender: TObject);
begin
  if SplashScreenVisible then
  begin
    Label1.Enabled := False;
    TrackBar1.Enabled := False;
    Button1.Enabled := False;
    HideSplashScreen;
    Button1.Caption := 'Show the splash screen';
    Button1.Enabled := True;
  end
  else
  begin
    Button1.Enabled := False;
    ShowSplashScreen;
    Button1.Caption := 'Hide the splash screen';
    Label1.Enabled := True;
    TrackBar1.Enabled := True;
    Button1.Enabled := True;    
  end;
end;

... ITD ...