BUG: Adding a record to a filtered tree store, and then unfiltering the store, inadvertently removes the record

[lesterleong]

There is a bug where adding records to filtered tree stores, and then unfiltering the store, causes the record to completely disappear. After diving in some more, I've noticed that this happens because the new record isn't added to the rootNode's unfilteredChildren collection, which then causes it to disappear when the store is unfiltered because this collection is copied to the children collection.

This is reproducible via the attachment included:
1. Unzip
2. Open bryntumbug.html in a browser
3. Click on "FILTER BY STEVE" to filter the store and grid by manager Steve
4. Click on "ADD AIRPORT" to add a new airport, JFK, to the store and grid. Notice that even though the store and grid are filtered by Steve, the new airport appears even though its only gate has a manager value of "Gabrielle".
5. Click on "CLEAR FILTERS" to clear the Steve filter. The JFK airport disappears. Even when clicking on "FILTER BY STEVE" again, the JFK airport does not appear.

[pmiklashevich]

Reproduced! Ticket here: https://app.assembla.com/spaces/bryntum/tickets/8797-records-are-not-shown-in-the-tree-after-clearing-filters-if-they-were-adde/details
Thanks for the report!