How to remove border of pop up menu in MFC

Question

I have custom class which is is inherited from CMenu class. I am trying to change the background color of the menu items. But the border of the menu items remain unchanged. Following are my overridden functions:

void CNewMenu::MeasureItem(LPMEASUREITEMSTRUCT lpMeasureItemStruct)
{
    lpMeasureItemStruct->itemHeight = 100;
    lpMeasureItemStruct->itemWidth = 150;
}

void CNewMenu::DrawItem(LPDRAWITEMSTRUCT lpDrawItemStruct)
{
    CRect rectFull(lpDrawItemStruct->rcItem); 
    COLORREF TextRect = COLORREF(RGB(0, 0, 0)); 
    CDC* pDC = CDC::FromHandle(lpDrawItemStruct->hDC);
    pDC->FillSolidRect(&rectFull, TextRect);
    pDC->TextOut(rectFull.left, rectFull.top, ((MenuObject*)lpDrawItemStruct->itemData)->m_strCaption);
}

How do I remove the border or change the color of the border?

I am referring to grey border around pop up menu