We have a product for web development in Object Pascal, Elevate Web Builder (http://www.elevatesoft.com/products?category=ewb&type=web) that includes an IDE with a WYSIWYG design environment (the IDE is written in Delphi for Windows). In order to supply the design environment, we had to write an emulation layer that mimics the DOM tree and can perform the necessary drawing operations to satisfy all DOM CSS style properties. This layer is ~80% of what you would need to implement a UI toolkit in native Object Pascal using Free Pascal. The last ~20% would be dealing with surfacing the native OS input controls (single-line edit, multi-line edit, etc.), which are just stubbed out right now because the design environment doesn't require them. We've considered finishing this last bit and making the whole thing available for Free Pascal.

Got it now, thanks. Interesting stuff.