#include <windows.h>

HINSTANCE hInstance;

class MainWnd {
public:
   MainWnd(int nCmdShow);
   ~MainWnd();
   HWND GetWindowId();
private:
   friend LRESULT CALLBACK MainWndProc(HWND hwnd, UINT iMsg, WPARAM wParam, LPARAM lParam);

   static bool first;
   int UserSizeChanging;
   HWND hMain;
   HWND hAttach;
};


MainWnd::MainWnd (int nCmdShow)
   : hAttach(NULL), UserSizeChanging(0)
{
   // do first time inits ?
   //
   if (first)
   {
       WNDCLASSEX wndcls;

       first = false;

       // register our StatBox window class
       //
       wndcls.cbSize = sizeof (WNDCLASSEX);
       wndcls.style = 0;
       wndcls.cbClsExtra = 0;
       wndcls.cbWndExtra = sizeof (HANDLE);
       wndcls.hInstance = hInstance;
       wndcls.hCursor = ::LoadCursor (NULL, IDC_ARROW);
       wndcls.lpszMenuName = NULL;
       wndcls.hbrBackground = (HBRUSH)(COLOR_BTNFACE + 1);
       wndcls.hIcon = ::LoadIcon (NULL, IDI_APPLICATION);
       wndcls.hIconSm = ::LoadIcon (NULL, IDI_APPLICATION);
       wndcls.lpfnWndProc = MainWndProc;
       wndcls.lpszClassName = "TkFriendly";

       ::RegisterClassEx (&wndcls);
   }

   hMain = ::CreateWindowEx (
           WS_EX_LEFT,
           "TkFriendly",
           "Tk container protocol example.",
           WS_OVERLAPPEDWINDOW,
           CW_USEDEFAULT, CW_USEDEFAULT, CW_USEDEFAULT, CW_USEDEFAULT,
           0L, 0L, hInstance, this
           );

   ::ShowWindow(hMain, nCmdShow);
   ::UpdateWindow(hMain);
}

MainWnd::~MainWnd () {
   if (hMain) ::SendMessage(hMain, WM_CLOSE, 0, 0);
}

HWND MainWnd::GetWindowId() {
   return hMain;
}

bool MainWnd::first = true;


LRESULT CALLBACK
MainWndProc(HWND hwnd, UINT iMsg, WPARAM wParam, LPARAM lParam)
{
   MainWnd *pMain = reinterpret_cast <MainWnd *>
           (::GetWindowLongPtr(hwnd, GWLP_USERDATA));

   switch (iMsg)
   {
       case WM_CREATE:
           // Supposedly, lpCreateParams has a DWORD alignment problem.
           // I don't know what this means for pointers.  I doubt much.
           //
           pMain = reinterpret_cast <MainWnd *>(((LPCREATESTRUCT)lParam)->lpCreateParams);

           // move the MainWnd class pointer into the
           // userdata of the window.
           //
           ::SetWindowLongPtr (hwnd, GWLP_USERDATA, reinterpret_cast <LONG_PTR>(pMain));
           return 0;

       case WM_CLOSE:
           ::DestroyWindow(hwnd);
           return 0;

       case WM_DESTROY:
           pMain->hMain = NULL;
           delete pMain;
           ::PostQuitMessage(0);
           return 0;

// ---------  Begin Tk container specials ----------

#define TK_CLAIMFOCUS     (WM_USER)
#define TK_GEOMETRYREQ    (WM_USER+1)
#define TK_ATTACHWINDOW   (WM_USER+2)
#define TK_DETACHWINDOW   (WM_USER+3)

       case TK_CLAIMFOCUS:
           if (wParam || (GetFocus() != NULL)) {
               ::SetFocus(pMain->hAttach);
           }
           return 0;

       case TK_GEOMETRYREQ:
           if (!pMain->UserSizeChanging) {

               // Make the client area to be the size given, but
               // we move the whole window.  Calc the additions
               // to get us there.

               wParam += 2 * GetSystemMetrics(SM_CXEDGE) + 3;
               lParam += GetSystemMetrics(SM_CYCAPTION) +
                       (2 * GetSystemMetrics(SM_CYEDGE) + 3);
               ::SetWindowPos(hwnd, NULL, 0, 0, wParam, lParam,
                       SWP_NOMOVE | SWP_NOZORDER | SWP_NOACTIVATE);
           }
           return 0;

       case TK_ATTACHWINDOW:
           pMain->hAttach = (HWND)wParam;
           ::SetParent(pMain->hAttach, hwnd);
           return 0;

       // We have found that as written, the return value of 0
       // prevents the generation of the TK_GEOMETRYREQ message in 
       // UpdateWrapper(TkWindow*) - see tk8.5.6/win/tkWinWm.c, 
       // lines 2299-2306.  When we returned a value of 1, the 
       // remainder of this code behaved as we expected.
       // -- AJS

       case TK_DETACHWINDOW:
           pMain->hAttach = NULL;
           ::PostMessage(hwnd, WM_CLOSE, 0, 0);
           return 0;

// ---------  End Tk container specials ----------

       case WM_ENTERSIZEMOVE:
           pMain->UserSizeChanging = 1;
           break;

       case WM_EXITSIZEMOVE:
           pMain->UserSizeChanging = 0;
           break;

       case WM_SIZE:
           if (wParam != SIZE_MINIMIZED && pMain->hAttach) {
               ::SetWindowPos(pMain->hAttach, NULL, 0, 0,
                       LOWORD(lParam), HIWORD(lParam),
                       SWP_NOMOVE | SWP_NOZORDER | SWP_NOACTIVATE);
           }
           return 0;

       case WM_PARENTNOTIFY:
           switch (LOWORD(wParam)) {
               case WM_LBUTTONDOWN:
               case WM_MBUTTONDOWN:
               case WM_RBUTTONDOWN:
                   ::SetFocus(pMain->hAttach);
                   return 0;

               case WM_DESTROY:
                   ::PostQuitMessage(0);
                   return 0;
           }
           break;

       case WM_ERASEBKGND:
           if (pMain->UserSizeChanging) return 1;
           break;
   }

   return ::DefWindowProc(hwnd, iMsg, wParam, lParam);
}


int WINAPI
WinMain(HINSTANCE hInst, HINSTANCE hPrevInstance, PSTR lpCmdLine, int nCmdShow)
{
   MSG msg;
   MainWnd *main;
   char buf[50];

   main = new MainWnd(nCmdShow);
   wsprintf(buf, "%ld", main->GetWindowId());
   MessageBox(main->GetWindowId(), buf, "Window ID is:", MB_OK);

   while (::GetMessage(&msg, NULL, 0, 0)) {
       ::TranslateMessage(&msg);
       ::DispatchMessage(&msg);
   }

   return msg.wParam;
}