Re: Glad I'm not a Windows UI dev
The WIMP interface is a solved problem
In principle, but not in practice.
There have been a number of reasons to revisit implementations. One is the advent of the mobile phone/tablet that not only has a much less precise pointer (the human finger) but also a significantly different resolution to the traditional computer screen (originally much less, latterly much more). Some of the assumptions built into original WIMP APIs are not great under those circumstances, especially if you want your application to work reasonably well across a range of screen sizes and resolutions.
Another is the advent of the GPU. When you're no longer directly drawing to a bitmap you might need to construct your API differently so it's clearer which objects can be rendered by the GPU later.
And a third is network transparency. That's particularly hard because it's difficult to predict how future technology might change assumptions about how the balance of work should be divided between client and server, but you can't easily add it later without possibly undermining the assumptions you might already have made in your local API.
And that's just the graphics primitives. When you come to high-level features such as checkboxes, buttons and text layout, the web stuck its oar in by doing things differently and we've been in search of convergence with desktop applications ever since.
But apart from that it's largely solved. In 2D. For now.