Win32 MDI 程序学习1

这个是从 Windows程序设计第五版 改来的；我还没完全理解；先初步看一下；

#include 
#include "resource.h"

#define INIT_MENU_POS    0
#define HELLO_MENU_POS   2

#define IDM_FIRSTCHILD   50000

LRESULT CALLBACK FrameWndProc(HWND, UINT, WPARAM, LPARAM);
BOOL    CALLBACK CloseEnumProc(HWND, LPARAM);
LRESULT CALLBACK HelloWndProc(HWND, UINT, WPARAM, LPARAM);

typedef struct tagHELLODATA
{
	UINT     iColor;
	COLORREF clrText;
}
HELLODATA, *PHELLODATA;

// global variables
TCHAR     szAppName[] = TEXT("MDIDemo");
TCHAR     szFrameClass[] = TEXT("MdiFrame");
TCHAR     szHelloClass[] = TEXT("MdiHelloChild");

HINSTANCE hInst;
HMENU     hMenuInit, hMenuHello;
HMENU     hMenuInitWindow, hMenuHelloWindow;

int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance,
	PSTR szCmdLine, int iCmdShow)
{
	HACCEL   hAccel;
	HWND     hwndFrame, hwndClient;
	MSG      msg;
	WNDCLASS wndclass;

	hInst = hInstanc