QAccessibleTree can use invalid indices

QAccessibleTree::indexFromLogical, QAccessibleTree::childCount() and QAccessibleTree::rowCount() use "treeView->d_func()->viewItems" to get index of element. But when tree widget isn't visible, these indices doesn't update. If that index contains internal pointer, as QSortFilterProxyModel indices, it can leads to use dangling pointer. With QPersistentIndex, which save this corrupted index into model, things getting worse.

I can suggest to call treeView->d_func()->executePostedLayout(), before use viewItems.