Win32 Window:

#include windows.h!

HWND hwndMain; 

LRESULT CALLBACK  WndProc( HWND hwnd,
                           UINT iMsg,
                           WPARAM wParam,
                           LPARAM lParam );


int APIENTRY  WinMain( HINSTANCE hInstance,
                       HINSTANCE hPrevInstance,
                       LPSTR lpszCmdLine,
                       int nCmdShow ) 
{ 
    MSG msg; 
    WNDCLASS wc; 
    UNREFERENCED_PARAMETER(lpszCmdLine); 
  
    wc.style         = 0; 
    wc.lpfnWndProc   = (WNDPROC) WndProc; 
    wc.cbClsExtra    = 0; 
    wc.cbWndExtra    = 0; 
    wc.hInstance     = hInstance; 
    wc.hIcon         = LoadIcon((HINSTANCE) NULL, IDI_APPLICATION); 
    wc.hCursor       = LoadCursor((HINSTANCE) NULL, IDC_ARROW); 
    wc.hbrBackground = (HBRUSH)GetStockObject(WHITE_BRUSH); 
    wc.lpszMenuName  =  "MainMenu"; 
    wc.lpszClassName = "MainWndClass"; 
 
    RegisterClass(&wc))
 
    hwndMain = CreateWindow( "MainWndClass",
                             "Win32 Window", 
                             WS_OVERLAPPEDWINDOW,
                             CW_USEDEFAULT,
                             CW_USEDEFAULT,
                             CW_USEDEFAULT,
                             CW_USEDEFAULT,
                             (HWND) NULL,
                             (HMENU) NULL,
                             hInstance,
                             (LPVOID) NULL); 
                             
    ShowWindow(hwndMain, nCmdShow); 
    UpdateWindow(hwndMain);
    
    while(GetMessage(&msg, (HWND) NULL, 0, 0)) 
    {
        TranslateMessage(&msg); 
        DispatchMessage(&msg); 
    }
 
    return msg.wParam; 
} 
 

LRESULT CALLBACK WndProc( HWND hwnd, 
                          UINT iMsg, 
                          WPARAM wParam, 
                          LPARAM lParam )
{
	

	switch( iMsg )
	{
		case WM_PAINT:
		{
			//MessageBox( hwnd, "Paint",  "Paint", S_OK );

		}
		break;


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