Clears all keys (and values) in the base ResourceDictionary. This does not clear any merged dictionary items.
Assembly: PresentationFramework (in PresentationFramework.dll)
If you need to clear merged dictionary items, obtain the particular dictionary from MergedDictionaries collection and specifically call on that ResourceDictionary, although typically the dictionaries are remote and you might not have access. Alternatively, remove the entire ResourceDictionary from MergedDictionaries by calling Remove on the generic collection.