C++Windowsh库绘制800x600的窗口设置255255255颜色边框232232232颜色的200x600的长方形位于00坐标并且设置背景为240242245颜色

以下是使用C++和Windows.h库绘制800x600窗口，设置颜色和绘制长方形的示例代码：

#include <Windows.h>

LRESULT CALLBACK WindowProc(HWND hwnd, UINT uMsg, WPARAM wParam, LPARAM lParam);

int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpCmdLine, int nCmdShow)
{
    // 注册窗口类
    WNDCLASS wc = {};
    wc.lpfnWndProc = WindowProc;
    wc.hInstance = hInstance;
    wc.lpszClassName = L"MyWindowClass";
    RegisterClass(&wc);

    // 创建窗口
    HWND hwnd = CreateWindowEx(
        0,
        L"MyWindowClass",
        L"Window Title",
        WS_OVERLAPPEDWINDOW,
        0, 0, 800, 600,
        NULL,
        NULL,
        hInstance,
        NULL
    );

    // 设置窗口背景颜色
    HBRUSH hBrush = CreateSolidBrush(RGB(240, 242, 245));
    SetClassLongPtr(hwnd, GCLP_HBRBACKGROUND, (LONG_PTR)hBrush);

    // 显示窗口
    ShowWindow(hwnd, nCmdShow);

    // 消息循环
    MSG msg = {};
    while (GetMessage(&msg, NULL, 0, 0))
    {
        TranslateMessage(&msg);
        DispatchMessage(&msg);
    }

    return 0;
}

LRESULT CALLBACK WindowProc(HWND hwnd, UINT uMsg, WPARAM wParam, LPARAM lParam)
{
    switch (uMsg)
    {
    case WM_PAINT:
    {
        PAINTSTRUCT ps;
        HDC hdc = BeginPaint(hwnd, &ps);

        // 绘制长方形
        RECT rect = { 0, 0, 200, 600 };
        HBRUSH hBrush = CreateSolidBrush(RGB(255, 255, 255));
        HBRUSH hOldBrush = (HBRUSH)SelectObject(hdc, hBrush);
        HPEN hPen = CreatePen(PS_SOLID, 1, RGB(232, 232, 232));
        HPEN hOldPen = (HPEN)SelectObject(hdc, hPen);
        Rectangle(hdc, rect.left, rect.top, rect.right, rect.bottom);
        SelectObject(hdc, hOldBrush);
        SelectObject(hdc, hOldPen);
        DeleteObject(hBrush);
        DeleteObject(hPen);

        EndPaint(hwnd, &ps);
        break;
    }
    case WM_DESTROY:
        PostQuitMessage(0);
        break;
    default:
        return DefWindowProc(hwnd, uMsg, wParam, lParam);
    }
    return 0;
}

上述代码会创建一个800x600的窗口，并将背景颜色设置为（240，242，245）。在WM_PAINT消息中，会绘制一个200x600的长方形，填充颜色为（255，255，255），边框颜色为（232，232，232），位于（0，0）坐标。

请注意，该代码需要在Windows平台上使用C++编译器进行编译和运行