[pawe]

Well, this is not really about filtering items in the data explorer window, but about showing "filtered child items" while browsing the tree:

If we could "stick to a search" while browsing the dataexplorer window (browsing the tree - but the search results window remains open instead of the child item window), this would not filter the tree, but be an equivalent of filtering the child items, given that the search is "restricted to the bold item" in the dateexplorer window.

An example: a software-database with a categorizing tree, each item has different attributes like "freeware/shareware", "X64-compatibility" etc. With the given feature above, it is easy to define a search and browse through all "x64 compatible freeware", without having to click forth and back in nested trees and searches.