I keep hoping for a Delphi Dartium-Embedded-Framework project, just because I use Delphi for desktop apps. But, the primary reason I am using Dart now (for HTML apps) is that I am trying to make to move away from traditional "native" apps (if possible). And, as ielian's original question hints at, there really does not seem to be any UI functionality available, even in this modern HTML5 world, that can come close to what I had available in Delphi. And, from Delphi, I somewhat regularly had the need to "embed" a good browser for rendering any and all HTML/CSS content, since so many apps seemed to store such "formatted" text now for various purposes.
There have been plenty of discussion threads about UI Widgets and the like, both here on the Dart group postings and elsewhere. And, the opinions about what should exist or should not vary considerably. Some argue that the web is not the place for "desktop like apps" or whatever, while others say the opposite. I really find the long-term outcome rather obvious: the web *will* (via HTML5/CSS/Dart/etc) end up with most all the controls and UI widgets that we have come to use on desktops/mobiles over the years. It is inevitable. Just look at all the UI-control projects out there and how they all start small and then add things like trees, grids, etc. It will come, but at what pace, and how splintered of standards and how many different control-sets to get what you want/need?
In the meantime, checkout the
Buckshot UI framework project... it is interesting, even as it is in "alpha". I expect more frameworks like this appear and mature in the coming months and years. I am playing with my own totally experimental
Dart/SVG "UI controls" project on github too, but I'd say it is very unlikely to ever become ready for desktop-app-replacement at my current pace of development; it is just too much work :)