当我将后缓冲区复制到屏幕时，功能d3ddev-> Present（）不起作用

Question

当我使用d3ddev->Present()将后台缓冲区复制到屏幕上时，什么也没发生（返回值为D3D_OK）。当我创建一个没有标题栏（例如WS_POPUP）的窗口时，它将起作用。有人可以告诉我为什么吗？谢谢。 对不起，英语不好。

win10，Direct3D9

window without titlebar

window with titlebar ...

//Game update function

void Game_Run(HWND hwnd)
{
    //make sure the Direct3D device is valid
    if (!d3ddev) return;
    //start rendering
    if (SUCCEEDED(d3ddev->BeginScene())) {
        //fill the surface with random color
        int r = rand() % 255;
        int g = rand() % 255;
        int b = rand() % 255;
        d3ddev->ColorFill(surface, NULL, D3DCOLOR_XRGB(r, g, b));
        //copy the surface to the backbuffer
        RECT rect;
        rect.left = rand() % SCREENW / 2;
        rect.right = rect.left + rand() % SCREENW / 2;
        rect.top = rand() % SCREENH / 2;
        rect.bottom = rect.top + rand() % SCREENH / 2;
        d3ddev->StretchRect(surface, NULL, backbuffer, &rect, D3DTEXF_NONE);
        //stop rendering
        d3ddev->EndScene();
        //copy the back buffer to the screen
        d3ddev->Present(NULL, NULL, NULL, NULL);
    }
    //check for escape key
    if (KEY_DOWN(VK_ESCAPE))
        PostMessage(hwnd, WM_DESTROY, 0, 0);
}
...
//create a new window
HWND hwnd = CreateWindow(
    "MainWindowClass",
    APPTITLE.c_str(),
    WS_POPUP,                   //it works
    //WS_OVERLAPPEDWINDOW,        it doesn't work
    CW_USEDEFAULT, CW_USEDEFAULT,
    SCREENW, SCREENH,
    NULL, NULL, hInstance, NULL);