@Graeme: You are aware that we're talking about Text-Mode, AFAIK UIDesigner is for GUI (Graphic User Interface) can UIDesigner do FV ?
Yes, that's exactly what I'm saying. The dialog designer will be a GUI application, but the code in generates will be Free Vision style dialogs.
eg: In a fork of UIDesigner you can register a "Button" control. In the UIDesigner that button will look like fpGUI's Button - but that's just looks, nothing else. The Object Inspector will display the properties
you registered for a button (fpGUI's UIDesigner doesn't simply use RTTI to extract property information like Lazarus or Delphi does). When you save the form design to a file, it can generate Free Vision dialog code. fpGUI's UIDesigner again doesn't use TComponent streaming for form designs - it has its own code parser and generator that doesn't use RTTI.
There is no reason why a Free Vision form designer must be a console application. Just like you don't need to use Free Pascal's Text IDE to write Console applications - you can use Lazarus IDE. A button is a button, a listbox is a listbox etc. It's what code gets generated that matters.