Migrate Settings to Desktop WinUI3 application

[crutkas]

Currently this is a XAML Island, WinUI 2.x with a WPF container app shell. Lets migrate this to be a pure desktop solution when the first opportunity comes.

Two primary requirements for WinUI3 to have are

1. Forward compatibility
2. Unpackaged app support (aka PowerToys not being installed as an MSIX)
3. PowerToysInterop needs to stop making FxFramework item and refactored

[crutkas]

Referenced in https://github.com/microsoft/PowerToys/wiki/Roadmap#best-effort-for-stabilization

[crutkas]

currently being investigated

[crutkas]

We need elevation support which currently is not supported

[sheikalthaf]

@crutkas I think now the multi window support is added in windows app sdk in latest release
https://github.com/microsoft/WindowsAppSDK/releases/tag/v1.0.1

I hope this helps

[crutkas]

@sheikalthaf we still need elevation. both come with 1.1

[MattBDev]

Is there a reason for relying on the unpackaged app support instead of allowing PowerToys to be installed as a MSIX?

[crutkas]

@MattBDev this is larger than packaged vs unpackaged. We need elevation and multi-window for WinUI 3. Having Settings itself be a packaged app that could be uninstalled could cause massive rippling effects.

[Samuel12321]

WASDK 1.1 preview1 has added support for multiple windows and elevation.

[Aaron-Junker]

This got implemented in the 0.58 update.