ObservableDictionary based on AVLTree with O(log N) insert/removal operations. Collection event aren't "Reset" but with proper positioning so it can be bound to the UI without affecting sort/group/highlight position on update.
Source code, usage and example can be found at...
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Library similar to Observablecollection, but it contains KeyValues and it can search by Key. Key is strictly string because of searching. The dictionary is intended to have large amount of items