Quote Originally Posted by wysota View Post
Why is speed an issue? Your model can "lag behind" if you scroll too fast but it should work. If the last index you loaded children for is e.g. row 100 and the last visible row is 120 then you need to load children for rows 101-120.

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.

Hopes it clear.