Select a record for a lookup via a tree view

There already is a tree view for N:N relations, but I think it would be great to be able to search for a record for a lookup field via a treeview. A common example would be

• selecting a product: the user would be default see the product families and is able to search these items or scroll through these and open the right family to drill down and select the right product.

Ideally the tree hierarchy could be based on 

• a self-referencing 1:N relationship such as products and product families
• a hierarchy based on another lookup/relationship from the "target" entity. 
  • Suppose  you have a lookup to select a country (custom entity)
  • Every country has a lookup (N:1) to another entity "Continent"
  • when opening the lookup search window, the user would see the lists of continents. The user is able to expand a continent which displays the countries linked to that continent and to select one. The selected country is completed in the lookup field.

• a third option would be able to use different levels, where the hierarchy is composed of different entities and different N:1 relationships (Continent - country - State) but might be too complex...