Windows-Apps-Hub/UnitedSets ? reverse-engineered prompt

Build me a Windows desktop app that lets me group separate app windows into tabs, kind of like the old Sets idea.

I want to be able to pick open windows, put them into one tabbed container, switch between them easily, and move a window out again if I want. It should feel native on Windows, with a clean UI and basic controls for creating a group, adding or removing windows, and closing the whole set. If it helps, make it handle the common stuff first and keep it stable, since this is meant to be something people can actually use day to day.

Please make it work as a polished beta with sensible defaults, and if you need to check current docs or Windows APIs online, go ahead.