WinApi c++ MDI관련 질문

#include <windows.h>
#include <commctrl.h>
#include "wchar.h"
#include "CommCtrl.h"
 
LRESULT CALLBACK WndProc(HWND,UINT,WPARAM,LPARAM);
LRESULT CALLBACK MDIChildProc(HWND hWnd,UINT iMessage,WPARAM wParam,LPARAM lParam);
HINSTANCE g_hInst;										//Instance Handle
HWND hWndMain;											//Main frame window handle
 
 
LPCTSTR lpszClass=TEXT("Measure");
 
	HWND hListTrace;
HWND hMDIClient;
static	int te4=0;
	wchar_t temp[200];
 
int APIENTRY WinMain(HINSTANCE hInstance,HINSTANCE hPrevInstance
	  ,LPSTR lpszCmdParam,int nCmdShow)
{
	HWND hWnd;
	MSG Message;
	WNDCLASS WndClass;
	g_hInst=hInstance;
 
	WndClass.cbClsExtra		=	0;
	WndClass.cbWndExtra		=	0;
	WndClass.hbrBackground	=	(HBRUSH)COLOR_APPWORKSPACE+1;//(COLOR_WINDOW+1);
	WndClass.hCursor		=	LoadCursor(NULL,IDC_ARROW);
	WndClass.hIcon			=	LoadIcon(NULL,IDI_APPLICATION);
	WndClass.hInstance		=	hInstance;
	WndClass.lpfnWndProc	=	WndProc;
	WndClass.lpszClassName	=	lpszClass;
	WndClass.lpszMenuName	=	NULL;
	WndClass.style			=	CS_HREDRAW | CS_VREDRAW;
	RegisterClass(&WndClass);
 
 
	hWnd	=	CreateWindow(lpszClass, lpszClass, WS_OVERLAPPEDWINDOW | WS_CLIPCHILDREN, 
							CW_USEDEFAULT, CW_USEDEFAULT, CW_USEDEFAULT, CW_USEDEFAULT, 
							NULL,(HMENU)NULL, hInstance, NULL);
	ShowWindow(hWnd,nCmdShow);
	hWndMain = hWnd;
 
 
 
    //UpdateWindow(hWnd);
 
	// For MDI Child window class enroll.
 
	WndClass.hbrBackground	=	(HBRUSH)COLOR_APPWORKSPACE+1;//(COLOR_WINDOW+1);
	WndClass.lpszClassName	=	L"MDIExamChild";
	WndClass.lpfnWndProc	=	MDIChildProc;
	WndClass.hIcon			=	LoadIcon(NULL,IDI_ASTERISK);
	WndClass.lpszMenuName	=	NULL;
	WndClass.cbWndExtra		=	sizeof(DWORD);		// Extra memory.
	RegisterClass(&WndClass);
 
 
	while (GetMessage(&Message,NULL,0,0)) {
		if (!TranslateMDISysAccel(hMDIClient, &Message)) {
			TranslateMessage(&Message);
			DispatchMessage(&Message);
		}
	}
	return (int)Message.wParam;
 
 
}
 
#define IDM_WINDOWCHILD 41000
	int temp4;
LRESULT CALLBACK WndProc(HWND hWnd,UINT iMessage,WPARAM wParam,LPARAM lParam)
{
	CLIENTCREATESTRUCT ccs;
	MDICREATESTRUCT mcs;
	static HANDLE hTimer;
	RECT rcClient;   
	int temp4;
 
 
	switch(iMessage) {
		case WM_CREATE:
			InitCommonControls();
			GetClientRect (hWnd, &rcClient); 
 
			ccs.hWindowMenu	=	NULL;
			ccs.idFirstChild	=		IDM_WINDOWCHILD;
			hMDIClient = CreateWindow(TEXT("MDICLIENT"), NULL, WS_CHILD | WS_VSCROLL | WS_HSCROLL | WS_CLIPCHILDREN  , 0, 0, 1000, 1000, hWnd,(HMENU)NULL, g_hInst, (LPSTR)&ccs);
			ShowWindow(hMDIClient, SW_SHOW);
			/**/
		hTimer = (HANDLE)SetTimer(hWnd, 1, 1000, NULL);
			mcs.szClass	=	TEXT("MDIExamChild");
						mcs.szTitle	=	TEXT("Child");
						mcs.hOwner	=	g_hInst;
						mcs.x	=	mcs.y	=	CW_USEDEFAULT;
						mcs.cx	=	mcs.cy	=	CW_USEDEFAULT;
						mcs.style	=	MDIS_ALLCHILDSTYLES;
						mcs.lParam = 0;
						SendMessage(hMDIClient, WM_MDICREATE, 0, (LPARAM)(LPMDICREATESTRUCT)&mcs);
			break;
 
		case WM_TIMER:
			KillTimer(hWnd, 1);
			mcs.szClass	=	TEXT("MDIExamChild");
						mcs.szTitle	=	TEXT("Child");
						mcs.hOwner	=	g_hInst;
						mcs.x	=	mcs.y	=	CW_USEDEFAULT;
						mcs.cx	=	mcs.cy	=	CW_USEDEFAULT;
						mcs.style	=	MDIS_ALLCHILDSTYLES;
						mcs.lParam = 0;
						SendMessage(hMDIClient, WM_MDICREATE, 0, (LPARAM)(LPMDICREATESTRUCT)&mcs);
			break;
		case WM_DESTROY:
			PostQuitMessage(0);
			return 0;
		}
	return(DefFrameProc(hWnd,hMDIClient,iMessage,wParam,lParam));
	//return(DefWindowProc(hWnd,iMessage,wParam,lParam));
}
 
 
HWND hTrace;
 
LRESULT CALLBACK MDIChildProc(HWND hWnd,UINT iMessage,WPARAM wParam,LPARAM lParam)
{
	LVITEM LI; 
	LVCOLUMN COL;
	PAINTSTRUCT ps;
	HDC hdc;
	TCHAR str[128];
	RECT rcClient;                       // The parent window's client area.
	time_t mytime;
	HANDLE hTimer;
 
	HFONT hFont=CreateFont(16, 6, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, TEXT("Consolas"));
 
 
 
	switch (iMessage) {
		case WM_CREATE:
			//InitCommonControls();
			hTrace = hWnd;
			GetClientRect (hWnd, &rcClient); 
 
			SetWindowLong(hWnd, 0, 1);
			SetWindowPos(hWnd, 0, 0, 0, 0, 0, SWP_NOSIZE);
			hTimer = (HANDLE)SetTimer(hWnd, 1, 1, NULL);
			hListTrace  = CreateWindow(WC_LISTVIEW, NULL, WS_CHILD | WS_VISIBLE | WS_BORDER | LVS_REPORT | LVS_SHOWSELALWAYS | LVS_OWNERDATA,
									 0, 0,
									 rcClient.right - rcClient.left,
                                     rcClient.bottom - rcClient.top,
									 hWnd,  (HMENU)5000, g_hInst, NULL);
			SendMessage(hListTrace, WM_SETFONT, (WPARAM)hFont, TRUE);
			SetFocus(hListTrace);
			SetWindowPos(hListTrace, NULL, 0, 0, rcClient.right - rcClient.left, rcClient.bottom - rcClient.top, SWP_NOZORDER);
 
			SetWindowLongPtr(hWnd,0,0);
			SetWindowPos(hWnd, 0, 0, 0, 0, 0, SWP_NOSIZE);
			ListView_SetExtendedListViewStyle( hListTrace,       LVS_EX_FULLROWSELECT | LVS_EX_GRIDLINES );
 
			COL.mask=LVCF_FMT | LVCF_WIDTH | LVCF_TEXT |LVCF_SUBITEM;
			COL.fmt=LVCFMT_LEFT;
			COL.cx=100;
			COL.pszText=TEXT("Time");			// 
			COL.iSubItem=0;
			ListView_InsertColumn(hListTrace,0,&COL);
 
 
			ListView_SetItemCount(hListTrace,2);
			return 0;
 
 
 
	case WM_NOTIFY:
		LPNMHDR hdr;
		NMLVDISPINFO *ndi;
		hdr=(LPNMHDR)lParam;
		ndi=(NMLVDISPINFO *)lParam;
		TCHAR tmp[300];
		if (hdr->hwndFrom == hListTrace) {
			switch (hdr->code) {
			case LVN_GETDISPINFO:
				if (ndi->item.iSubItem == 0) {
					if ((ndi->item.mask & LVIF_TEXT) == LVIF_TEXT) {
						wsprintf(tmp, L"%d", te4);
						lstrcpy(ndi->item.pszText, tmp);
					}
				} else {
					switch (ndi->item.iSubItem) {
					case 1:
						wsprintf(tmp, L"%d", ndi->item.iItem);
						break;/*
					case 2:
						wsprintf(tmp, L"%d", ndi->item.iItem);
						break;
					case 3:
						wsprintf(tmp, L"%s", ndi->item.iItem);
						break;
					case 4:
						wsprintf(tmp, L"%d", ndi->item.iItem);
						break;
					case 5:
						wsprintf(tmp, L"%d", ndi->item.iItem);
						break;*/
					}
					lstrcpy(ndi->item.pszText, tmp);
				}
				return 0;
			case LVN_ODCACHEHINT:
				return 0;
			case LVN_ODFINDITEM:
				return -1;
			}
		}
 
		case WM_SIZE:
			GetClientRect (hWnd, &rcClient); 
			SetWindowPos(hListTrace, NULL, 0, 0, rcClient.right - rcClient.left, rcClient.bottom - rcClient.top, SWP_NOZORDER);
			return 0;
 
		case WM_PAINT:
			hdc=BeginPaint(hWnd, &ps);
			wsprintf(str,L"Child window");
			TextOut(hdc,0,0,str,lstrlen(str));
			EndPaint(hWnd, &ps);
			return 0;
		case WM_TIMER:
			ListView_SetItemCount(hListTrace,2);
			te4++;
		break;
 
	}
 
	return(DefMDIChildProc(hWnd, iMessage, wParam, lParam));
}