Question: Are there currently any file picker options available when running a WinUI3 app in PartialTrust mode?

[karter16]

Are there currently any file picker options available when running a WinUI3 app in PartialTrust mode?

I have an existing UWP app which I have chosen to migrate to a WinUI3-based app. I am building and packaging the app in PartialTrust mode for the following reasons:

1: Having been a UWP app to begin with the app was already running inside an AppContainer, etc.
2: I want to continue to be able to offer the app on the MS Store without having to request FullTrust for the app, which is unnecessary. The app is for use on PCs that are used during live productions and as a result my customers are fairly suspicious of anything that requires unfettered access to their devices, I'd therefore much prefer to not have to require FullTrust.

What I'm looking to understand is whether there are any file-picker-like options available to me at this point in time. I've done a fair amount of reading and investigation and as I understand it I'm not able to go the file picker route, as using a file picker requires giving it an HWND and WinRT.Interop.InitializeWithWindow can't be run in PartialTrust mode, so from what I can tell that option is off the table for me.

Are there any other suggestions/options that I could look at at this point in time (short of building my own filepicker type of thing)? Any suggestions/leads would be appreciated.

Note: I do realise that I have brought this on myself, my fallback option is to keep on as a UWP app, I just like to keep up to speed with the latest developments and options, hence wanting to explore this.

Thanks,

Matt

[DarranRowe]

What makes you think the file pickers can't be used in partial trust mode? All partial trust does is put the application into a lightweight app container, it is still running as a desktop application.

[JaiganeshKumaran]

The problem here is that the file picker under partial trust assumes there's a CoreWindow on the current thread, which is obviously not true in WinUI 3 apps.

[karter16]

The problem here is that the file picker under partial trust assumes there's a CoreWindow on the current thread, which is obviously not true in WinUI 3 apps.

Yes that's right, CoreWindow doesn't exist in WinUI 3 land, and you obviously can't pass an HWND in PartialTrust mode, hence anyone wanting to use a filepicker in WinUI 3 PartialTrust mode is stuck at present.

[JaiganeshKumaran]

For now, you can enable broad file system access and create your own file picker. Obviously not a good idea.

[Rybasum]

microsoft/microsoft-ui-xaml#4100 (comment)
This is an old issue and Microsoft seems not to care. File pickers is something most apps do. Hence, I infer they don't want us to put non-UWP apps in AppContainer for some reason.

[DarranRowe]

@Rybasum
There is something else people could do to help.
Since the pickers and app containers are a Windows component, this should be reported through the Feedback Hub. I did open a bug report for this over a year ago and nobody has been upvoting it. I also can't find any other bug reports on the Feedback Hub related to the pickers. So, when the only bug report on the Feedback Hub related to the pickers has 2 upvotes, how important does that make this issue seem?