Create New Windows

unit CreateAWindowu;

interface

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

type
  TForm1 = class(TForm)
    Button1: TButton;
    procedure Button1Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.DFM}

{ Register the Window Class }
function RegisterClass: Boolean;
var
  WindowClass: TWndClass;
begin
  {setup our new window class}
  WindowClass.Style := CS_HREDRAW or CS_VREDRAW;           {set the class styles}
  WindowClass.lpfnWndProc := @DefWindowProc;               {point to the default window procedure}
  WindowClass.cbClsExtra := 0;                             {no extra class memory}
  WindowClass.cbWndExtra := 0;                             {no extra window memory}
  WindowClass.hInstance := hInstance;                      {the application instance}
  WindowClass.hIcon := 0;                                  {no icon specified}
  WindowClass.hCursor := 0;                                {no cursor specified}
  WindowClass.hbrBackground := COLOR_WINDOW;               {use a predefined color}
  WindowClass.lpszMenuName := nil;                         {no menu}
  WindowClass.lpszClassName := 'TestClass';                {the registered class name}

  {now that we have our class set up, register it with the system}
  Result := Windows.RegisterClass(WindowClass) <> 0;
end;

procedure TForm1.Button1Click(Sender: TObject);
var
  hWindow: HWND;
begin
  {Step 1: Register our new window class}
  if not RegisterClass then
  begin
    ShowMessage('RegisterClass failed');
    Exit;
  end;

  {Step 2: Create a window based on our new class}
  hWindow := CreateWindow('TestClass',           {the registered class name}
                          'New Window',          {the title bar text}
                          WS_OVERLAPPEDWINDOW,   {a normal window style}
                          CW_USEDEFAULT,         {default horizontal position}
                          CW_USEDEFAULT,         {default vertical position}
                          CW_USEDEFAULT,         {default width}
                          CW_USEDEFAULT,         {default height}
                          0,                     {no owner window}
                          0,                     {no menu}
                          hInstance,             {the application instance}
                          nil                    {no additional information}
                          );

  {Step 3: If our window was created successfully, display it}
  if hWindow <> 0 then
  begin
    ShowWindow(hWindow, SW_SHOWNORMAL);
    UpdateWindow(hWindow);
  end
  else
  begin
    ShowMessage('CreateWindow failed');
    Exit;
  end;

end;

end.