This example is composed of three files:

• Source code(modeless.cpp)
• Resource definitions(resources.h)
• Resource script(script.rc)

//=============================================================================
//MODELESS DIALOG - Copyright © 2000,2005 Ken Fitlike
//=============================================================================
//API functions used: CreateDialog,DestroyWindow,DispatchMessage,GetLastError,
//GetMessage,IsDialogMessage,IsWindow,LoadImage,MAKEINTRESOURCE,MessageBox,
//PostQuitMessage,PostMessage,SendMessage,TranslateMessage,WinMain,wsprintf.
//=============================================================================
//This demonstrates the creation of a modeless dialog box.
//=============================================================================
#include <windows.h>  //include all the basics
#include <tchar.h>    //string and other mapping macros
#include <string>
#include <vector>
#include "resources.h"

//define an unicode string type alias
typedef std::basic_string<TCHAR> ustring;
//=============================================================================
//message processing function declarations
INT_PTR CALLBACK DlgProc(HWND hwnd,UINT uMsg,WPARAM wParam,LPARAM lParam);
void OnCommand(const HWND,int,int,const HWND);
INT_PTR OnInitDlg(const HWND,LPARAM);

//non-message function declarations
inline int ErrMsg(const ustring&);
//=============================================================================
int WINAPI WinMain(HINSTANCE hInst,HINSTANCE,LPSTR,int)
{
HWND hDlg=CreateDialog(hInst,MAKEINTRESOURCE(IDD_DIALOG1),0,DlgProc);

if (!hDlg)
  {
  ErrMsg(_T("CreateDialog failed."));
  return 0;
  }
  
//start message loop - windows applications are 'event driven' waiting on user,
//application or system signals to determine what action, if any, to take. Note 
//that an error may cause GetMessage to return a negative value so, ideally,  
//this result should be tested for and appropriate action taken to deal with 
//it(the approach taken here is to simply quit the application).
MSG msg;
while (GetMessage(&msg,0,0,0)>0)
  {
  //get default keyboard message handling for dialog box eg control tabbing
  if (!IsWindow(hDlg) || !IsDialogMessage(hDlg,&msg))
    {
    TranslateMessage(&msg);
    DispatchMessage(&msg);
    }
  }
return static_cast<int>(msg.wParam);
}
//=============================================================================
INT_PTR CALLBACK DlgProc(HWND hwnd,UINT uMsg,WPARAM wParam,LPARAM lParam)
{
switch (uMsg)
  {
  case WM_COMMAND:
    {
    OnCommand(hwnd,LOWORD(wParam),HIWORD(wParam),
              reinterpret_cast<HWND>(lParam));
    return 0;
    }
  case WM_DESTROY:
    PostQuitMessage(0);    //signal end of application
    return 0;
  case WM_INITDIALOG:
    {
    return OnInitDlg(hwnd,lParam);
    }
  default:
    return 0;  //let system deal with msg
  }
}
//=============================================================================
void OnCommand(const HWND hwnd,int id,int notifycode,const HWND hCntrl)
{
//handles WM_COMMAND message of the modal dialogbox
switch (id)
  {
  case IDOK:        //RETURN key pressed or 'ok' button selected
  case IDCANCEL:    //ESC key pressed or 'cancel' button selected
    DestroyWindow(hwnd);
  }
}
//=============================================================================
INT_PTR OnInitDlg(const HWND hwnd,LPARAM lParam)
{
//set the small icon for the dialog. IDI_APPLICATION icon is set by default 
//for winxp
SendMessage(hwnd,WM_SETICON,ICON_SMALL,
            reinterpret_cast<LPARAM>(LoadImage(0,IDI_APPLICATION,IMAGE_ICON,
                                               0,0,LR_SHARED)));
//ensure focus rectangle is properly drawn around control with focus
PostMessage(hwnd,WM_KEYDOWN,VK_TAB,0);
return TRUE;
}
//=============================================================================
inline int ErrMsg(const ustring& s)
{
return MessageBox(0,s.c_str(),_T("ERROR"),MB_OK|MB_ICONEXCLAMATION);
}
//=============================================================================

//=============================================================================
//Resource script constants for Modeless Dialog example.
//=============================================================================
#define IDD_DIALOG1                200

//=============================================================================
//MODELESS DIALOG - Copyright (c) 2000,2005 Ken Fitlike
//resource script
//=============================================================================
#if !defined __BORLANDC__
#include <afxres.h>
#endif
#include "resources.h"
//=============================================================================
//Resource languages: Codes for languages and sub-languages are declared in 
//winnt.h eg. for US english replace SUBLANG_ENGLISH_UK with SUBLANG_ENGLISH_US
//eg. for FRENCH replace LANG_ENGLISH with LANG_FRENCH and then replace 
//SUBLANG_ENGLISH_UK with either SUBLANG_FRENCH,SUBLANG_FRENCH_BELGIAN,
//SUBLANG_FRENCH_CANADIAN,SUBLANG_FRENCH_SWISS,SUBLANG_FRENCH_LUXEMBOURG,
//SUBLANG_FRENCH_MONACO depending on which national or regional variation of
//the language corresponds best with your requirements.
//
LANGUAGE LANG_ENGLISH, SUBLANG_ENGLISH_UK  
//=============================================================================
//Dialog
//=============================================================================
IDD_DIALOG1 DIALOGEX 0, 0, 252, 149
STYLE DS_CENTER | WS_MINIMIZEBOX | WS_MAXIMIZEBOX | WS_POPUP | WS_VISIBLE | 
      WS_CAPTION | WS_SYSMENU | WS_THICKFRAME
CAPTION "Dialog Box: Modeless"      
FONT 8, "MS Sans Serif"
  {
  DEFPUSHBUTTON   "OK",IDOK,22,62,50,14
  PUSHBUTTON      "Cancel",IDCANCEL,111,63,50,14
  }
//=============================================================================