>>559
こんな感じです。一応ウィンドウモードに切り替えることも考慮してます。

RECT rect;
SetRect(&rect, 0, 0, WIDTH, HEIGHT);
DWORD style = (FULLSCREEN) ? WS_POPUP :(WS_CAPTION|WS_SYSMENU|WS_BORDER|WS_MINIMIZEBOX);
AdjustWindowRect(&rect, style, FALSE);
int width = rect.right - rect.left;
int height = rect.bottom - rect.top;

WNDCLASS wc;
ZeroMemory(&wc, sizeof(WNDCLASS));
wc.hbrBackground= (HBRUSH)GetStockObject(BLACK_BRUSH);
wc.hCursor = LoadCursor(NULL,IDC_ARROW);
wc.hInstance = hInst;
wc.lpfnWndProc= MsgProc;
wc.lpszClassName= CAPTION;
if(RegisterClass(&wc) == 0) return 0;

HWND hWnd = CreateWindow(CAPTION,CAPTION,style,CW_USEDEFAULT,CW_USEDEFAULT,width,height,NULL,NULL,hInst,NULL);
if(hWnd == NULL) return 0;

if(FAILED(InitD3D(hWnd))){return 0;}

if(FULLSCREEN)
{
SetWindowPos(hWnd, NULL, 0, 0, 0, 0, SWP_NOMOVE | SWP_NOSIZE | SWP_NOZORDER | SWP_FRAMECHANGED);
}
ImmAssociateContext(hWnd,0);
ShowWindow(hWnd, SW_SHOW);
UpdateWindow(hWnd);