Why the shadow of the character remains there after redraw the window?

Question

Using WTL and Graphics,I rewrite an list view tool,like: ,but after click the Name or Phone Number header to sort, it appears like:.

Seems that the old one still there, but not so clear,whats wrong?

The Core Draw Code:

    void _DrawItem(HDC hDC, LPDRAWITEMSTRUCT lpDrawItemStruct) 
    {
            ...
            CDCHandle       dcx;
            Gdiplus::Graphics grap(hDC);

            CRect rcTmp;
            GetClientRect(&rcTmp);
            dcx.Attach(hDC);
            BOOL bBackColor = TRUE;
            if ((lpDrawItemStruct->itemID % 2) == 0) 
            {
                bBackColor = FALSE;
            }

            Gdiplus::SolidBrush mySolidBrush(Gdiplus::Color(235, 235, 235,235));
            if (pItem->getOver() || pItem->getChecked())
            {
                mySolidBrush.SetColor(Gdiplus::Color(215, 0, 0, 215));
            }else{
                if (bBackColor)
                {
                    mySolidBrush.SetColor(Gdiplus::Color(235, 235, 235, 235));
                }else{
                    mySolidBrush.SetColor(Gdiplus::Color(255, 255, 255, 255));
                }
            }
            grap.FillRectangle(&mySolidBrush, lpDrawItemStruct->rcItem.left , lpDrawItemStruct->rcItem.top, nColumWidth,
                lpDrawItemStruct->rcItem.bottom - lpDrawItemStruct->rcItem.top);

Answer 1

Just a guess but your alpha transparency value is not opaque so filling the rect with 235,235,235,235 will blend with the old content. Probably need a 255 in there for alpha.