Microsoft is holding its Windows Developer Day event today for the Creators Update, where it announced the Windows Platform bug tracker. It's similar to the Platform Issues portal that was introduced for Edge back in April.
As you can see from the slide, it won't just allow you to track bugs, but you can also track new features. You can view progress on fixing these too, and file new bugs.
It also contains a Windows platform roadmap. According to the slide, that includes UWP capabilities, so it presumably doesn't include all OS features that are planned. This is a bit curious though, as Microsoft also launched a roadmap for Windows 10 back in April, but at this point, it seems to be all but abandoned, with nothing listed under the 'In Public Preview' tab.
This tool is bound to be helpful for developers and Microsoft alike, where developers need to know about what's next for the Universal Windows Platform, and Microsoft needs to know how best to make it better. The site hasn't launched just yet, but once it is, you can find it here.