[solved] Problem with the "Prev Bookmark"

int CXTPSyntaxEditCtrl::CalculateVisibleRow(int nStartDocumentRow, int nDocumentRow)
{
    return max(CalculateVisibleRow_(nStartDocumentRow, nDocumentRow), 1);
}

int CXTPSyntaxEditCtrl::CalculateVisibleRow_(int nStartDocumentRow, int nDocumentRow)
{
    int nVisRow = nDocumentRow - nStartDocumentRow + 1;
    int nNextCollapsedRow = nStartDocumentRow - 1;
    const int nRowCount = GetRowCount();

    POSITION pos = GetLineMarksManager()->FindNextLineMark(nNextCollapsedRow, xtpEditLMT_Collapsed);
    while (pos != NULL)
    {
        XTP_EDIT_LMDATA* pData = GetLineMarksManager()->GetNextLineMark(pos, xtpEditLMT_Collapsed);
        if (pData && pData->m_nRow >= nNextCollapsedRow) // mark should be not within previous collapsed block
        {
            if (pData->m_nRow >= nDocumentRow) // finish if mark is greater then row to calculate for
                break;

            XTP_EDIT_COLLAPSEDBLOCK* pCoDBlk = (XTP_EDIT_COLLAPSEDBLOCK*)pData->m_Param.GetPtr();
            if (!pCoDBlk)
                continue;

            int nBlkEnd = min(nRowCount, pCoDBlk->collBlock.lcEnd.nLine);
            if (nBlkEnd > nDocumentRow)
                nBlkEnd = nDocumentRow;        // DocumentRow in invisible(collapsed) block
            
            int nHiddenRows = nBlkEnd - pCoDBlk->collBlock.lcStart.nLine;

            nVisRow -= nHiddenRows;
            nNextCollapsedRow = pData->m_nRow + nHiddenRows;
        }
    }
    return nVisRow;
}

void CXTPSyntaxEditCtrl::PrevBookmark()
{
    CXTPSyntaxEditLineMarksManager* pMgr = GetLineMarksManager();
    if (!pMgr)
    {
        ASSERT(FALSE);
        return;
    }
    int nRow = GetCurRow();
    int nVisRow = CalculateVisibleRow_(m_nTopRow, GetCurrentDocumentRow());

    // move up to the prev bookmark before the current collapsed block area
    int nPrevRow = nRow;
    do {
        pMgr->FindPrevLineMark(--nPrevRow, xtpEditLMT_Bookmark);
    } while (nPrevRow > 0 && CalculateVisibleRow_(m_nTopRow, nPrevRow) == nVisRow);

    if (nPrevRow < 0)
    {
        POSITION posLast = pMgr->GetLastLineMark(xtpEditLMT_Bookmark);
        XTP_EDIT_LMDATA* pData = pMgr->GetLineMarkAt(posLast, xtpEditLMT_Bookmark);
        nPrevRow = pData ? pData->m_nRow : -1;
    }
    if (CalculateVisibleRow_(m_nTopRow, nPrevRow) == nVisRow)
    {
        nPrevRow = -1;
    }

    if (nPrevRow >= 0)
    {
        SetCurPos(nPrevRow, 1);

        Invalidate(FALSE);
    }
}

void CXTPSyntaxEditCtrl::NextBookmark()
{
    CXTPSyntaxEditLineMarksManager* pMgr = GetLineMarksManager();
    if (!pMgr)
    {
        ASSERT(FALSE);
        return;
    }

    int nRow = GetCurRow();
    int nVisRow = CalculateVisibleRow_(m_nTopRow, GetCurrentDocumentRow());

    // move down to the next bookmark after the current collapsed block area
    int nNextRow = nRow;
    do {
        pMgr->FindNextLineMark(++nNextRow, xtpEditLMT_Bookmark);
    } while (nNextRow > 0 && CalculateVisibleRow_(m_nTopRow, nNextRow) == nVisRow);

    if (nNextRow < 0)
    {
        // find first line mark
        POSITION posFirst = pMgr->GetFirstLineMark(xtpEditLMT_Bookmark);
        XTP_EDIT_LMDATA* pData = pMgr->GetNextLineMark(posFirst, xtpEditLMT_Bookmark);
        nNextRow = pData ? pData->m_nRow : -1;
    }

    if (CalculateVisibleRow_(m_nTopRow, nNextRow) == nVisRow)
    {
        nNextRow = -1;
    }

    if (nNextRow >= 0)
    {
        SetCurPos(nNextRow, 1);

        Invalidate(FALSE);
    }
}