简单的程序

代码：
#include   <windows.h> 
#include   <stdlib.h> 
#include   <string.h> 
#include<tchar.h>
#include"kuang.h"
long   WINAPI   WndProc(HWND   hWnd,   UINT   iMessage,   UINT   wParam,   LONG   lParam); 
BOOL   InitWindowsClass(HINSTANCE   hInstance); 
BOOL   InitWindows(HINSTANCE   hInstance,   int   nCmdShow); 
HINSTANCE hInstance;
HWND hWnd;
int nCheckBoxSt;
HWND hwndPush,hwndDefPush,hwndRadio,hwndAutoRadio,hwndCheckBox,hwndAutoCheckBox,hwndGroupBox;int  WINAPI   WinMain( HINSTANCE   hInstance, 
HINSTANCE   hPrevInstance, 
LPSTR   lpCmdLine, 
int   nCmdShow) 
{ 
MSG   Message; if   (!   InitWindowsClass(hInstance)) 
return   FALSE; 
if   (!   InitWindows(hInstance,nCmdShow)) 
return   FALSE; 
while   (GetMessage(&Message,   0,   0,   0))   { 
TranslateMessage(&Message); 
DispatchMessage(&Message); 
} return   Message.wParam; 
} long   WINAPI   WndProc( HWND   hWnd, 
UINT   iMessage, 
WPARAM   wParam, 
LPARAM   lParam) 
{ int X=50,Y=30;switch   (iMessage)   { 
case WM_CREATE:
hwndPush=CreateWindow(_T("button"),_T("这里是一个按钮，按我吧！"),BS_PUSHBUTTON|WS_CHILD|WS_VISIBLE,
X,Y,
240,25,
hWnd,
(HMENU)IDB_DEFPUSHBUTTON,
hInstance,
NULL);
hwndDefPush=CreateWindow(_T("BUTTON"),_T("这是默认按钮，按下试试看！"),BS_DEFPUSHBUTTON|WS_CHILD|WS_VISIBLE,
X,Y+30,
240,25,
hWnd,
(HMENU)IDB_DEFPUSHBUTTON,
hInstance,
NULL);
hwndRadio=CreateWindow(_T("BUTTON"),
_T("单选按钮，你喜欢吗？"),
BS_RADIOBUTTON|WS_CHILD|WS_VISIBLE,
X,Y+60,
240,25,
hWnd,
(HMENU)IDB_RADIOBUTTON,
hInstance,
NULL);
hwndAutoRadio=CreateWindow(_T("BUTTON"),
_T("自动圆形按钮，看看有何区别?"),
BS_AUTORADIOBUTTON|WS_CHILD|WS_VISIBLE,
X,Y+90,
240,25,
hWnd,
(HMENU)IDB_AUTORADIOBUTTON,
hInstance,
NULL);
        hwndCheckBox=CreateWindow(_T("BUTTON"),
_T("复选框"),
BS_CHECKBOX|WS_CHILD|WS_VISIBLE,
X,Y+20,
240,25,
hWnd,
(HMENU)IDB_CHECKBOX,
hInstance,
NULL);
        hwndAutoCheckBox=CreateWindow(_T("BUTTON"),_T("自动复选框，你会用吗？"),
BS_AUTOCHECKBOX|WS_CHILD|WS_VISIBLE,
X,Y+150,
240,25,
hWnd,
(HMENU)IDB_AUTOCHECKBOX,
hInstance,
NULL);
hwndGroupBox=CreateWindow(_T("BUTTON"),_T("组框"),BS_GROUPBOX|WS_CHILD|WS_VISIBLE,
X+290,Y+30,
100,140,
hWnd,
(HMENU)IDB_GROUPBOX,
hInstance,
NULL);
break;
case WM_COMMAND:
switch(LOWORD(wParam))
 {
case IDB_PUSHBUTTON:
SetWindowText(hwndPush,_T("你已按下了按钮！"));
break;
case IDB_DEFPUSHBUTTON:
SetWindowText(hwndDefPush,_T("按钮已被按下"));
            break;
case IDB_RADIOBUTTON:
SendMessage(hwndRadio,BM_SETCHECK,1,0);
break; case IDB_AUTORADIOBUTTON:
break;
  }
break;
case IDB_CHECKBOX:
    
         if(nCheckBoxSt==0)
 {
   SendMessage(hwndCheckBox,BM_SETCHECK,1,0);
   nCheckBoxSt=1;
 }
 else
 {
 SendMessage(hwndCheckBox,BM_SETCHECK,0,0);
 nCheckBoxSt=0;
 
 }
 break;
case IDB_AUTOCHECKBOX:
break;
case IDB_GROUPBOX:
break;
     case   WM_DESTROY: 
     PostQuitMessage(0);
     break;default: 
return (DefWindowProc(hWnd,   iMessage,   wParam,   lParam)); 
} return   0; 
} BOOL   InitWindows(HINSTANCE   hInstance,   int   nCmdShow) 
{ 
hWnd   =   CreateWindow( 
_T("控件"), 
_T("菜单显示实例程序 "), 
WS_OVERLAPPEDWINDOW, 
CW_USEDEFAULT, 
CW_USEDEFAULT, 
CW_USEDEFAULT, 
CW_USEDEFAULT,  
NULL, 
NULL, 
hInstance, 
NULL 
); 
if   (!   hWnd) 
return   FALSE;ShowWindow(hWnd,   nCmdShow); 
UpdateWindow(hWnd); return   TRUE; 
} BOOL   InitWindowsClass(HINSTANCE   hInstance) 
{ 
WNDCLASS   WndClass; 
WndClass.hInstance=hInstance;
WndClass.style   =   0; 
WndClass.cbClsExtra   =   0; 
WndClass.cbWndExtra   =   0; 
WndClass.hbrBackground   =   (HBRUSH)GetStockObject(WHITE_BRUSH); 
WndClass.hCursor   =   LoadCursor(NULL,   IDC_ARROW); 
WndClass.hIcon   =   LoadIcon(NULL,   IDI_APPLICATION); 
WndClass.lpfnWndProc   =   WndProc; 
WndClass.lpszClassName   =  _T( "控件"); 
WndClass.lpszMenuName   =  NULL; 
return   RegisterClass(&WndClass); 
}
问题：窗口 不能关闭？？？WHY