Affiche
I've been working on a cross-platform GUI system called Affiche. The basic idea is to separate an application's UI semantics from the toolkit that actually renders it. The same application can currently be presented using native Win32, Cocoa/AppKit, Qt6, GTK3, GTK4, Swing, or a web browser. The UI can run locally or be rendered remotely by a client, without the application itself being rewritten for that environment. I've also been working on a declarative layout format and, lately, a visual designer. It started as a rewrite of an architecture I worked on many years ago, mostly because I wanted to see how far the idea could be pushed with modern systems. It has turned into a considerably larger project than I expected. Still private and very much under development, but I'm curious whether other people have run into the same problem: maintaining applications that need to survive changes in GUI toolkits, operating systems, deployment models, or client environments.