FileOpenPicker throw Invalid Window handle exception in Project Reunion 0.5 desktop app

[gcaughey]

Describe the bug

FileOpenPicker throws Invalid Window handle exception on PickSingleFileAsync()

Steps to reproduce the bug

Steps to reproduce the behavior:

1. Step through the following code:

var picker = new FileOpenPicker();
var file = await picker.PickSingleFileAsync();

Expected behavior

picker.PickerSingleFileAsync() should show FileOpenPicker

Screenshots

Version Info

NuGet package version:

WinUI 3 - Project Reunion 0.5 Preview: 0.5.0-prerelease

Windows app type:

UWP	Win32
No	Yes

This fails running on Win32 but does not fail running in UWP app model.

Windows 10 version	Saw the problem?
Insider Build (21332)	Yes
October 2020 Update (19042)
May 2020 Update (19041)
November 2019 Update (18363)
May 2019 Update (18362)
October 2018 Update (17763)
April 2018 Update (17134)
Fall Creators Update (16299)
Creators Update (15063)

Device form factor	Saw the problem?
Desktop	Yes
Xbox
Surface Hub
IoT

Additional context

This app runs without error when running under UWP.

[Marv51]

I had the same issue and this worked for me: #4167

        [ComImport, System.Runtime.InteropServices.Guid("3E68D4BD-7135-4D10-8018-9FB6D9F33FA1"), InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
        public interface IInitializeWithWindow
        {
            void Initialize([In] IntPtr hwnd);
        }

        [DllImport("user32.dll", ExactSpelling = true, CharSet = CharSet.Auto, PreserveSig = true, SetLastError = false)]
        public static extern IntPtr GetActiveWindow();

        var picker = new FileOpenPicker();
        var initializeWithWindowWrapper = picker.As<IInitializeWithWindow>();
        initializeWithWindowWrapper.Initialize(GetActiveWindow());
        var file = await picker.PickSingleFileAsync();

[gcaughey]

I'm getting a compiler error on this line of code:
var initializeWithWindowWrapper = picker.As<IInitializeWithWindow>();
Member 'FileOpenPicker.As()' cannot be accessed with an instance reference.

Interestingly the ContentDialog issue that was mentioned in your issue appears to work now.

[FreddyDgh]

@gcaughey add using WinRT; to use the As<T>() extension method.

[gcaughey]

Thanks - that does indeed solve the compiler error. But now I'm getting a new exception on PickSingleFileAsync: Error HRESULT E_FAIL has been returned from a call to a COM component.

[FreddyDgh]

@gcaughey I just tried it out and unfortunately, it doesn't look like the FileTypeFilter gets set automatically either. So, you'll need to add yet another line to your current monstrosity: picker.FileTypeFilter.Add("*");

[gcaughey]

Excellent! This makes a very usable workaround. Thanks!

[StephenLPeters]

Closing as a duplicate of #4167

[YareYareO]

I have a WinUi3 project and this worked for me just now. FYI. Thanks alot to everyone!