팝업 윈도우 (WS_POPUPWINDOW, WM_NCHITTEST)

#include <windows.h>

LRESULT CALLBACK WndProc(HWND,UINT,WPARAM,LPARAM);
HINSTANCE g_hInst;
HWND hWndMain;
LPSTR lpszClass="Class";

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)GetStockObject(LTGRAY_BRUSH);
    WndClass.hCursor=LoadCursor(NULL,IDC_ARROW);
    WndClass.hIcon=LoadIcon(NULL,IDI_APPLICATION);
    WndClass.hInstance=hInstance;
    WndClass.lpfnWndProc=(WNDPROC)WndProc;
    WndClass.lpszClassName=lpszClass;
    WndClass.lpszMenuName=NULL;
    WndClass.style=CS_HREDRAW | CS_VREDRAW;
    RegisterClass(&WndClass);

    hWnd=CreateWindow(lpszClass,lpszClass,WS_POPUPWINDOW,    // WS_POPUPWINDOW 팝업 윈도우 형태 WS_POPUP하면 테두리도 없음
        10,10,200,100,
        NULL,(HMENU)NULL,hInstance,NULL);
    ShowWindow(hWnd,nCmdShow);
    hWndMain=hWnd;
    
    while(GetMessage(&Message,0,0,0)) {
        TranslateMessage(&Message);
        DispatchMessage(&Message);
    }
    return Message.wParam;
}

LRESULT CALLBACK WndProc(HWND hWnd,UINT iMessage,WPARAM wParam,LPARAM lParam)
{
    HDC hdc;
    PAINTSTRUCT ps;
    char Mes[]="팝업 윈도우입니다";
    UINT nHit;

    switch(iMessage) {
    case WM_CREATE:
        return 0;
    case WM_PAINT:
        hdc=BeginPaint(hWnd, &ps);
        SetBkMode(hdc,TRANSPARENT);
        TextOut(hdc,10,10,Mes,strlen(Mes));
        EndPaint(hWnd, &ps);
        return 0;
    case WM_NCHITTEST:
        nHit=DefWindowProc(hWnd,iMessage,wParam,lParam);
        if (nHit==HTCLIENT)
            nHit=HTCAPTION;                // 클릭시 CAPTION을 클릭한 효과를 준다. 즉 윈도우를 선택해 이동 할 수 잇다.
        return nHit;
    case WM_DESTROY:
        PostQuitMessage(0);
        return 0;
    }
    return(DefWindowProc(hWnd,iMessage,wParam,lParam));
}