Comment 6 for bug 583330

I've recently fixed filteredtree count (now the "all tasks" count is always right), but I think the count keeping could be refactored a bit.
What we count must always be equal to len(self.displayed_nodes), so we could create a derived class from dict that keeps the count.
Does anybody know if len(dict) is O(1) in python (in other words, does dict contain a updated count)?

Anyway, the "tasks with no tags" count is taken from a filtered tree. That number is wrong, so there must be something with that class.