int QWinInputContext::reconvertString(RECONVERTSTRING *reconv)
{
    QWidget *w = focusWidget();
    if(!w)
        return -1;

    Q_ASSERT(w->testAttribute(Qt::WA_WState_Created));
    QVariant srndTextV = w->inputMethodQuery(Qt::ImSurroundingText);
    if (!srndTextV.isValid())
        return -1;
    QString srndText = srndTextV.toString();

    const int memSize = sizeof(RECONVERTSTRING)+(srndText.size()+1)*sizeof(ushort);
    // If memory is not allocated, return the required size.
    if (!reconv)
       return memSize;

    QVariant srndCaretV = w->inputMethodQuery(Qt::ImCursorPosition);
    if (!srndCaretV.isValid()) {
        return -1;
    }
    const int srndCaret = srndCaretV.toInt();

    QVariant selTextV = w->inputMethodQuery(Qt::ImCurrentSelection);
    if (!selTextV.isValid()) {
        return -1;
    }
    const QString selText = selTextV.toString();

    // Determine surrounding anchor position.
    int srndAnchor = srndCaret;
    const QVariant srndAnchorV = w->inputMethodQuery(Qt::ImAnchorPosition);
    if (srndAnchorV.isValid()) {
        srndAnchor = srndAnchorV.toInt();
        if ((srndAnchor < 0) || (srndText.size() < srndAnchor)) {
            return -1;
        }
        if (srndCaret != srndAnchor) {
            const int start = QMIN(srndCaret, srndAnchor);
            const int width = QABS(srndCaret - srndAnchor);
            if (srndText.midRef(start, width) != selText) {
                return -1;
            }
        }
    } else if (!selText.isEmpty()) {
        const int selSize = selText.size();
        if (selText == srndText.midRef(srndCaret, selSize)) {
            srndAnchor = srndCaret + selSize;
        } else if (selText == srndText.midRef(srndCaret - selSize, selSize)) {
            srndAnchor = srndCaret - selSize;
        } else {
           return -1;
        }
    }

    // Map selection to dwCompStr.
    // No selection assumes current caret as selectedText without length.
    const int selStart = QMIN(srndCaret, srndAnchor);

    reconv->dwSize = memSize;
    reconv->dwVersion = 0;

    reconv->dwStrLen = srndText.size();
    reconv->dwStrOffset = sizeof(RECONVERTSTRING);
    reconv->dwCompStrLen = selText.size(); // TCHAR count.
    reconv->dwCompStrOffset = selStart * sizeof(ushort); // byte count.
    reconv->dwTargetStrLen = reconv->dwCompStrLen;
    reconv->dwTargetStrOffset = reconv->dwCompStrOffset;
    memcpy((char*)(reconv+1), srndText.utf16(), srndText.size()*sizeof(ushort));

    // If no selection, ask windows Ime to choose target range.
    HIMC imc = getContext(w->effectiveWinId());
    if (!imc)
        return -1;

    if (!::ImmSetCompositionStringW(imc, SCS_QUERYRECONVERTSTRING, reconv, memSize, NULL, 0)) {
        releaseContext(w->effectiveWinId(), imc);
        return -1;
    }

    // Target fields have been filled by Win IME.
    int targetStart = reconv->dwTargetStrOffset / sizeof(ushort);
    int targetLength = reconv->dwTargetStrLen;

    if (!selText.isEmpty()) {
        if (targetLength != selText.size()) {
            return -1;
        }
        targetLength = 0;
    }

    // Clear target for Ime string to sit in.
    QInputMethodEvent delEvent;
    delEvent.setCommitString(QString(), targetStart - srndCaret, targetLength);
    qt_sendSpontaneousEvent(w, &delEvent);

    // Ime String for target returns with WM_IME_COMPOSITION.
    releaseContext(w->effectiveWinId(), imc);
    return memSize;
}