CListCtrl 拖动滚动条闪烁，添加LVS_EX_DOUBLEBUFFER风格，重绘的网格线不显示。解决方法

CListCtrl 拖动滚动条闪烁，添加LVS_EX_DOUBLEBUFFER风格，重绘的网格线不显示。
如题， 添加LVS_EX_DOUBLEBUFFER风格后，拖动滚动条，重绘的网格线就不显示了，非要鼠标在列表上晃动一下才会显示出来，而且拖动一列的大小时，那一列的网格也不显示了，也需要再次晃动一下鼠标。请问这是为什么？

重绘的网格线的代码
ON_NOTIFY(NM_CUSTOMDRAW, IDC_LIST1, &CMy33Dlg::OnNMCustomdrawList1)

void CMy33Dlg::OnNMCustomdrawList1(NMHDR *pNMHDR, LRESULT *pResult)
{
NMLVCUSTOMDRAW* pLVCD = reinterpret_cast<NMLVCUSTOMDRAW*>(pNMHDR);  
*pResult = 0;
CListCtrl* pList = (CListCtrl*)GetDlgItem(IDC_LIST1);

if((pList->GetStyle() & LVS_TYPEMASK) == LVS_REPORT) 
{ 
CClientDC dc(this); 
CPen newPen, *oldPen; 
newPen.CreatePen(PS_SOLID, 1, RGB(0,0,0)); 
oldPen = dc.SelectObject(&newPen); 


CHeaderCtrl* pHeader = pList->GetHeaderCtrl(); 
int nColumnCount = pHeader->GetItemCount(); 
RECT rect; 
pHeader->GetClientRect(&rect); 
int top = rect.bottom; 
int left = rect.left;
pList->GetWindowRect(&rect); 
int left1 = rect.left;
ScreenToClient(&rect);

CRect ss;
pList->GetClientRect(&ss);

CRect dlgRect;
GetWindowRect(&dlgRect);

CRect dlgRect1;
GetClientRect(&dlgRect1);

int borderx = 0 - pList->GetScrollPos(SB_HORZ); 

for(int i = 0; i < nColumnCount;i++) 
{
borderx += pList->GetColumnWidth(i); 

if(borderx + (rect.left - dlgRect1.left)+2 >= ss.right + 12) break; 
if (borderx + (rect.left - dlgRect1.left)+2 <= left1 - dlgRect.left + 2) continue;

dc.MoveTo(borderx + (rect.left - dlgRect1.left)+2, top + (rect.top - dlgRect1.top)+2); 
dc.LineTo(borderx + (rect.left - dlgRect1.left)+2, ss.bottom+9);//rect.bottom - (dlgRect1.bottom - rect.bottom)); 
}

if(!pList->GetItemRect(0,&rect,LVIR_BOUNDS)) 
return; 

int height = rect.bottom - rect.top; 

pList->GetWindowRect(&rect); 


//int width = rect.right - rect.left - 10;

for(int i = 1; i<= pList->GetCountPerPage(); i++) 
{ 
dc.MoveTo(rect.left - dlgRect.left + 2, top + height*(i+1) -2); 
dc.LineTo(ss.right + 12, top + height*(i+1) - 2); 
} 
dc.SelectObject(oldPen); 
newPen.DeleteObject(); 
} 
}


------解决方案--------------------
回去找找资料，明天再来回答。