I would love to see one even as simple as Phoenix[1] for C++11
[1] http://byuu.org/phoenix/
phoenix is a C++11-based GUI meta-toolkit. It is designed as a simple, light-weight API that can be used to create up to moderately complex GUIs; which can then be used to target other popular toolkits, such as the Windows API, GTK+ and Qt.
The idea behind phoenix is to limit one's self to the bare minimum functionality necessary to create standard user interfaces. By using such a small subset, the overall portability of your application is improved. For instance, porting phoenix to another toolkit is at best a weekend project.
While other toolkits such as GTK+ and Qt are cross-platform, they require massive (5MB+) run-times to be distributed with your application. They also tend to be slightly buggy, and their look-and-feel usually ends up somewhere in the uncanny valley. Close, but not perfect.
phoenix allows you to target 100% native APIs for your chosen platform. And by being so light-weight and simplistic, it does not require any run-time DLLs, nor does it add much of anything onto your executable size. phoenix is compiled as a single object file, and adds roughly 50KB onto your executable size.