Windows 子窗体不显示解决思路

#include <windows.h>

#define ID_LIST     1
#define ID_TEXT     2
#define NUM (sizeof(listitem)/sizeof(listitem[0])

struct{
    int index;
    TCHAR *text;
} 
listitem[]={
    1,TEXT("北京市"),
    2,TEXT("湖南省"),
    3,TEXT("湖北省"),
    4,TEXT("江西省")
};

LRESULT CALLBACK WndProc (HWND, UINT, WPARAM, LPARAM);
int WINAPI WinMain (HINSTANCE hInstance, HINSTANCE hPrevInstance,PSTR szCmdLine, int iCmdShow)
{
        
           static TCHAR szAppName[] = TEXT ("Environ") ;
           HWND                                 hwnd ;
           MSG                                  msg ;
           WNDCLASS                      wndclass ;
           wndclass.style = CS_HREDRAW | CS_VREDRAW ;
           wndclass.lpfnWndProc= WndProc ;
           wndclass.cbClsExtra= 0 ;
           wndclass.cbWndExtra= 0 ;
           wndclass.hInstance= hInstance ;
           wndclass.hIcon = LoadIcon (NULL, IDI_APPLICATION) ;
           wndclass.hCursor= LoadCursor (NULL, IDC_ARROW) ;
           wndclass.hbrBackground = (HBRUSH) (COLOR_WINDOW + 1) ;
           wndclass.lpszMenuName = NULL ;
           wndclass.lpszClassName  = szAppName ;
           if (!RegisterClass (&wndclass))
           {
                  MessageBox (  NULL, TEXT ("This program requires Windows NT!"), szAppName, MB_ICONERROR) ;
                  return 0 ;
           }
           hwnd = CreateWindow (szAppName, TEXT ("Environment List Box"),WS_OVERLAPPEDWINDOW,CW_USEDEFAULT, CW_USEDEFAULT,CW_USEDEFAULT, CW_USEDEFAULT,NULL, NULL, hInstance, NULL) ;
           ShowWindow (hwnd, iCmdShow) ;
           UpdateWindow (hwnd) ;
           while (GetMessage (&msg, NULL, 0, 0))
            {
            TranslateMessage (&msg) ;
            DispatchMessage (&msg) ;
           }
           return msg.wParam ;
        
}


LRESULT CALLBACK WndProc (HWND hwnd, UINT message, WPARAM wParam,LPARAM lParam)
{
    static int cyChar,cxChar;
    static HWND hwndList,hwndText,hwndButton,hwndCheck;
    TCHAR format[]=TEXT("宽=%d,高=%d");
    TCHAR buffer[20];
    switch(message){
        case WM_CREATE:
            cyChar=HIWORD(GetDialogBaseUnits());
            cxChar=LOWORD(GetDialogBaseUnits());
            wsprintf(buffer,format,cyChar,cxChar);
            hwndList=CreateWindow(TEXT("list"),TEXT("=请选择="),WS_CHILD | WS_VISIBLE|WS_BORDER | LBS_STANDARD,
                                  20,30,40,20,hwnd,(HMENU)ID_LIST,(HINSTANCE) GetWindowLong (hwnd, GWL_HINSTANCE),NULL);
            hwndText=CreateWindow(TEXT("text"),NULL,
                WS_CHILD | WS_VISIBLE | WS_HSCROLL | WS_VSCROLL | WS_BORDER | ES_LEFT | ES_MULTILINE | ES_AUTOHSCROLL | ES_AUTOVSCROLL,0,50,100,20,hwnd,(HMENU)10,(LPCREATESTRUCT(lParam))->hInstance,NULL);
             hwndButton =CreateWindow(TEXT("button"),TEXT("点击"),WS_CHILD | WS_VISIBLE | BS_DEFPUSHBUTTON,0, 0, 20 * cxChar, 7 * cyChar / 4,hwnd, (HMENU)6,((LPCREATESTRUCT) lParam)->hInstance, NULL) ;
            hwndCheck=CreateWindow(TEXT("button"),TEXT("复选"),WS_CHILD | WS_VISIBLE | BS_AUTOCHECKBOX,0, 100, 20 * cxChar, 7 * cyChar / 4,hwnd, (HMENU)7,((LPCREATESTRUCT) lParam)->hInstance, NULL) ;
            return 0;
        case  WM_SIZE :
                wsprintf(buffer,format,cyChar,cxChar);
                //MoveWindow (hwndText, 0, cyChar*4, cxChar*20,cyChar,TRUE) ;
                return 0 ;
        case WM_SETFOCUS:
            SetFocus(hwndText);
            return 0;
        case WM_DESTROY:
                PostQuitMessage(0);
                break;
    }
     return DefWindowProc(hwnd, message, wParam, lParam);
        
}