catch Left most down element in QTreeView

[wysota]

Got the point but, ItemAt(viewPort()->rect()->bottomLeft()) (I put it in the slot connected to vertical scroll bar moved) But it is not able to find the element when i scroll the element too fast, But it is able to find this element when I scroll slowly. I really couldn't get where to put this statement ItemAt(viewPort()->rect()->bottomLeft()) (Or looking for an another way to get the element).

So what does itemAt() return if it "isn't able to find the element"?

misunderstanding might be : I am not talking about top level items they can be load with canFetchMore() & fetchMore(). This functions are not working properly for non top level & root items (Can see my links above).

The prob is, I have 100 top level items loaded in my view, And now I expanded 1st top level item which as 1000 child's, Now what I did I loaded only 500 child's Now my view has Top level 1st item & its child's (hardly 30 to 40 child's) visible. Now if i scroll my view down My idea is to catch 500th child Of 1st top level Item & add remaining 500 child's but I am not able to find it with ItemAt(viewPort()->rect()->bottomLeft()).
When I scroll little fast, this function is not able to find that (basically its not able to find all items which are coming from down entry point, skipping some). & I am using this statement in slot connected to vertical scroll bar moved.

If itemAt() returns top-level index with row = 2 and previously you fetched items with parent set to row = 1 then based on that you can deduce you should fetch those missing items from first top-level row.