Draggable grid rerenders

[ykshev]

I've tried a new observe('todosAutorun', state.projectTodos, handle, cursor); approach and found a serious performance leak compared to the plain action. I have a sortable grid where every item has an order position number. After changing position of one item I updated order number of every item in the collection. If I use action with store.items.replace(data) I will have just one rerender of the grid, but if I use observe('todosAutorun', state.projectTodos, handle, cursor); I will get action 'Images: document changed' (Object) for every item, because its order number has been changed and this action triggers the reaction of whole list rerendering. And if there is a list of 40 items, I will get 40 rerenders.