rem: KMHeaderItem( QListView* parent, int msgId, QString key = QString::null)
add: KMHeaderItem( QListViewItem* parent, int msgId, QString key = QString::null)
context:     KMHeaderItem( QListView* parent, int msgId, QString key = QString::null)    : KListViewItem( parent ),	  mMsgId( msgId ),	  mKey(key)  {    irefresh();  }