Как закрасить белую линию между панелью меню и клиентской областью окна?

#include <windows.h> 
 
LRESULT CALLBACK WndProc(HWND hWnd, UINT uMsg, WPARAM wParam, LPARAM lParam);
 
struct
{
    COLORREF text = RGB(200, 200, 250);
    COLORREF clientBorder = RGB(120, 0, 0); 
    COLORREF clientBackground = RGB(100, 100, 100);
    COLORREF itemBorder = RGB(0, 0, 255);
    COLORREF itemBackground = RGB(0, 120, 0);
    COLORREF pink = RGB(255, 0, 255);
} colorTheme;
 
int WINAPI WinMain(HINSTANCE hInst, HINSTANCE hPrevInst, LPSTR lpCmdLine, int nCmdShow)
{
    MSG msg;
 
    WNDCLASSEX wc;
    wc.cbSize = sizeof(wc);
    wc.style = CS_HREDRAW | CS_VREDRAW;
    wc.lpfnWndProc = WndProc;
    wc.lpszMenuName = NULL;
    wc.lpszClassName = "MainWindow";
    wc.cbWndExtra = NULL;
    wc.cbClsExtra = NULL;
    wc.hIcon = LoadIcon(NULL, IDI_WINLOGO);
    wc.hIconSm = LoadIcon(NULL, IDI_WINLOGO);
    wc.hCursor = LoadCursor(NULL, IDC_ARROW);
    wc.hbrBackground = CreateSolidBrush(colorTheme.clientBackground);
    wc.hInstance = hInst;
 
    RegisterClassEx(&wc);
 
    HWND hMainWnd = CreateWindow(
        "MainWindow",
        "MainWindow",
        WS_OVERLAPPEDWINDOW,
        100, 100, 450, 120,
        (HWND)NULL, NULL, HINSTANCE(hInst), NULL);
 
    HMENU hMenu = CreateMenu();
    HMENU hMenuSub1 = CreatePopupMenu();
    HMENU hMenuSub2 = CreatePopupMenu();
    HMENU hMenuSub3 = CreatePopupMenu();
    AppendMenu(hMenu, MF_OWNERDRAW | MF_POPUP, (UINT)hMenuSub1, "SubMenu1");
    AppendMenu(hMenuSub1, MF_OWNERDRAW, 0, "Item01");
    AppendMenu(hMenuSub1, MF_OWNERDRAW, 0, "Item02");
    AppendMenu(hMenuSub1, MF_OWNERDRAW, 0, "Item03");
    AppendMenu(hMenuSub1, MF_OWNERDRAW, 0, "Item04");
    AppendMenu(hMenuSub1, MF_OWNERDRAW, 0, "Item05");
    AppendMenu(hMenu, MF_OWNERDRAW | MF_POPUP, (UINT)hMenuSub2, "SubMenu2");
    AppendMenu(hMenu, MF_OWNERDRAW | MF_POPUP, (UINT)hMenuSub3, "SubMenu3");
 
    MENUINFO menuInfo;
    menuInfo.cbSize = sizeof(menuInfo);
    menuInfo.fMask = MIM_BACKGROUND;
    menuInfo.hbrBack = CreateSolidBrush(colorTheme.pink);
    SetMenuInfo(hMenu, &menuInfo);
    SetMenu(hMainWnd, hMenu);
 
    ShowWindow(hMainWnd, nCmdShow);
 
    while (GetMessage(&msg, NULL, NULL, NULL)) {
        TranslateMessage(&msg);
        DispatchMessage(&msg);
    }
    return msg.wParam;
}
 
LRESULT CALLBACK WndProc(HWND hWnd, UINT uMsg, WPARAM wParam, LPARAM lParam)
{
    switch (uMsg) {
    case WM_PAINT:
    {
        PAINTSTRUCT ps;
        HDC hDC = BeginPaint(hWnd, &ps);
 
        HFONT hApplicationFont;
        LOGFONT applicationFont;
        applicationFont.lfHeight = 16;
        applicationFont.lfWidth = 6;
        applicationFont.lfEscapement = 0;
        applicationFont.lfOrientation = 0;
        applicationFont.lfWeight = FW_NORMAL;
        applicationFont.lfItalic = FALSE;
        applicationFont.lfUnderline = FALSE;
        applicationFont.lfStrikeOut = FALSE;
        applicationFont.lfCharSet = DEFAULT_CHARSET;
        applicationFont.lfOutPrecision = OUT_DEFAULT_PRECIS;
        applicationFont.lfClipPrecision = CLIP_DEFAULT_PRECIS;
        applicationFont.lfQuality = ANTIALIASED_QUALITY;
        applicationFont.lfPitchAndFamily = DEFAULT_PITCH;
        strcpy_s(applicationFont.lfFaceName, "Arial");
        hApplicationFont = CreateFontIndirectA(&applicationFont);
        SelectObject(hDC, hApplicationFont);
 
        SelectObject(hDC, GetStockObject(DC_PEN));
        SetDCPenColor(hDC, colorTheme.clientBorder);
        SelectObject(hDC, GetStockObject(DC_BRUSH));
        SetDCBrushColor(hDC, colorTheme.clientBackground);
        RECT clientRect;
        GetClientRect(hWnd, &clientRect);
        Rectangle(hDC, 0, 0, clientRect.right, clientRect.bottom);
 
        EndPaint(hWnd, &ps);
        break;
    }
    case WM_MEASUREITEM:
    {
        LPMEASUREITEMSTRUCT itemStruct = (LPMEASUREITEMSTRUCT)lParam;
        const char* str = (const char*)(itemStruct->itemData);
        SIZE strSize;
        HDC hDC = GetDC(hWnd);          
        GetTextExtentPoint32(hDC, str, lstrlen(str), &strSize);
        itemStruct->itemWidth = strSize.cx;
        itemStruct->itemHeight = 30;
        ReleaseDC(hWnd, hDC);
 
        return TRUE;
        break;
    }
    case WM_DRAWITEM:
    {
        LPDRAWITEMSTRUCT itemStruct = (LPDRAWITEMSTRUCT)lParam;
        HDC hDC = itemStruct->hDC;
        SelectObject(hDC, GetStockObject(DC_PEN));
        SetDCPenColor(hDC, colorTheme.itemBorder);
        SelectObject(hDC, GetStockObject(DC_BRUSH));
        SetDCBrushColor(hDC, colorTheme.itemBackground);
        SetTextColor(hDC, colorTheme.text);
        SetBkMode(hDC, TRANSPARENT);
 
        Rectangle(hDC, itemStruct->rcItem.left,
                       itemStruct->rcItem.top,
                       itemStruct->rcItem.right,
                       itemStruct->rcItem.bottom + 1);
        DrawText(hDC, (const char*)(itemStruct->itemData), -1, &(itemStruct->rcItem), DT_SINGLELINE | DT_CENTER | DT_VCENTER);
        break;
    }
    case WM_DESTROY:
    {
        PostQuitMessage(NULL);
        break;
    }
    default:
        return DefWindowProc(hWnd, uMsg, wParam, lParam);
    }
    return NULL;
}