EtoileUI is a high-level UI toolkit for Étoilé where elements visible on screen are abstract nodes to which pluggable aspects can be bound. The same uniform tree structure is used to describe any kind of structured content (composite document, application User Interface etc.) and the role of each node can be entirely changed at runtime by altering the aspects bound to it.

All User Interface concerns such as layouts, tools, action handlers, styles, model objects etc. are pluggable aspects which can be easily reused and recombined.