Overview
- Screenshots posted on BlueSky by PhantomOfearth and reported by multiple outlets revealed a hidden, modern Properties dialog in Windows 11 preview builds that appeared between Tuesday and Thursday and shows up for items in the Recycle Bin in reported build 26300.8935.
- The new window is built with WinUI 3 and supports dark mode, matching Microsoft’s public plan to bring WinUI to more Shell components and in‑box experiences.
- Microsoft has tied the work to its Windows K2 effort to optimize WinUI performance so modernized UI elements start faster and integrate more smoothly with the rest of Windows 11.
- A core technical risk is that many third‑party tools inject legacy HWND‑based tabs into the classic Properties dialog and Microsoft will need a reverse‑islands or embedding strategy to host those pages inside WinUI without breaking extensions.
- The dialog is hidden in experimental preview and not yet released to the public so the key next steps to watch are Microsoft’s rollout timeline, the company’s approach to hosting legacy tabs, and WinUI performance fixes that address cold‑start costs.