Theia is a platform for building IDEs and tools. Initially and quite naturally, it best supported textual editing for coding. However, now that Theia has matured and adoption is quickly growing, other use cases are gaining traction for Theia. One very important use case that was and is well supported with Eclipse RCP and EMF is building domain-specific modeling tools. These tools often show and edit structured data in trees, forms and diagrams and rely on model validation, analysis and simulation, model comparison and merging, code generation.