How can i make xtptaskpanel group looks like this?

I want to make my xtptaskpanel groups looks like this:



I writed the follow code to achieve my goals:

class CTaskPanelBkgGroup : public CXTPTaskPanelGroup
{
public:
     CTaskPanelBkgGroup(int id)
     {
          m_nBackgroundImage=id;
     }
};

CTaskPanelBkgGroup * pGroup=(CTaskPanelBkgGroup *)m_wndTaskPanel.GetGroups()->Add(new CTaskPanelBkgGroup(0),0);
pGroup->SetCaption("test);
pItem=pGroup->AddTextItem("test");
pItem->SetType(xtpTaskItemTypeLink);
pItem->SetID(0);

But it doesn't work,I get a access violation error when i tried to set the background image of the group.So there are two questions:

1.how can i set the background image of a xtptaskpanel group?

2.how can i set the background image of a xtptaskpanel?

thanks,