KisDocument *KisDocument::lockAndCreateSnapshot()
{
    KisDocument *doc = lockAndCloneForSaving();
    if (doc) {
        // clone palette list
        doc->d->paletteList = doc->d->clonePaletteList(doc->d->paletteList);
        doc->d->documentResourceStorage = doc->d->documentResourceStorage->clone();
    }
    return doc;
}