Преподавание программирования

#include <windows.h> 

HINSTANCE hi; 
LPSTR CLASS_NAME="TMP_CLASS"; 
LPSTR BUTTONCLASS="BUTTON"; 

LRESULT CALLBACK WndProc(HWND hwnd,UINT mes,WPARAM wp,LPARAM lp) { 
switch(mes) { 
case WM_CREATE: 
   ShowWindow(hwnd,SW_SHOW); 
   CreateWindow(BUTTONCLASS,"Левая",WS_CHILD|BS_CENTER|WS_TABSTOP|BS_PUSHBUTTON|WS_VISIBLE,24,138,130,28,hwnd,(HMENU)101,hi,NULL); 
   CreateWindow(BUTTONCLASS,"Правая",WS_CHILD|BS_CENTER|WS_TABSTOP|BS_PUSHBUTTON|WS_VISIBLE,164,138,130,28,hwnd,(HMENU)102,hi,NULL); 
   break; 
case WM_QUIT: return(0);
case WM_CLOSE: 
   MessageBox(NULL,"А вот и нет!","Перехват",MB_OK|MB_SETFOREGROUND|MB_ICONEXCLAMATION); 
   return(0);
case WM_DESTROY: 
   PostQuitMessage(0);
   return(0); 
case WM_COMMAND: switch(LOWORD(wp)) { 
   case 101: 
      MessageBox(NULL,"Нажал левую кнопку","Приложение",MB_OK|MB_SETFOREGROUND|MB_ICONINFORMATION); 
      break; 
   case 102: 
      MessageBox(NULL,"Нажал правую кнопку","Приложение",MB_OK|MB_SETFOREGROUND|MB_ICONINFORMATION); 
   } 
} 
return(DefWindowProc(hwnd,mes,wp,lp)); 
}//=============================================

int WINAPI WinMain(HINSTANCE hins,HINSTANCE hpi,LPSTR cmd,int ncmd) { 
MSG msg; 
WNDCLASSEX w; 
LOGBRUSH brush; 

hi=hins; 
brush.lbStyle=BS_SOLID; 
brush.lbColor=RGB(0xC0,0xC0,0xC0); 
memset(&w,0,sizeof(WNDCLASSEX)); 
w.cbSize=sizeof(WNDCLASSEX); 
w.style=CS_HREDRAW|CS_VREDRAW; 
w.lpfnWndProc=WndProc; 
w.hInstance=hi; 
w.cbWndExtra=36; 
w.hbrBackground=CreateBrushIndirect(&brush); 
w.lpszClassName=CLASS_NAME; 
RegisterClassEx(&w); 

CreateWindowEx(WS_EX_LEFT,CLASS_NAME,"Незакрывающееся приложение", 
WS_SYSMENU|WS_TILED,30,10,320,200,NULL,NULL,hi,NULL); 

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