[BUG] [Windows] The second popup will fail to show after MAUI 8.0.60

[GuidoNeele]

Is there an existing issue for this?

• I have searched the existing issues

Did you read the "Reporting a bug" section on Contributing file?

• I have read the "Reporting a bug" section on Contributing file: https://github.com/CommunityToolkit/Maui/blob/main/CONTRIBUTING.md#reporting-a-bug

Current Behavior

This is a very strange issue. Since MAUI version 8.0.60 the second popup will fail. Only the second time you want to show a popup will fail. The popup will not show up and if you are using CommunityToolkit.MVVM [RelayCommand] the button (triggering the popup) will be disabled, because the Task will not return. See video of the problem.

Every_second_popup_via_popupservice_fails.mp4

Expected Behavior

The popup should always be shown also the second popup.

Steps To Reproduce

1. Download latest version of CommunityToolkit
2. Open Directory.Build.props in root folder of project
3. Change MauiPackageVersion property to 8.0.60
4. Open Visual Studio and run the sample application
5. Go to Views / Multiple Popups Page
6. Click on "Simple Popup"
7. Close the popup by clicking outside the popup
8. Click on "C# Binding Popup"
9. The button will be disabled and the popup will not appear

Link to public reproduction project repository

https://github.com/CommunityToolkit/Maui

Environment

- .NET MAUI CommunityToolkit: 9.0.1
- OS: Windows 11 (net8.0-windows10.0.19041.0)
- .NET MAUI: 8.0.60

Anything else?

To prevent the button from disabling while using CommunityToolkit.MVVM is to use [RelayCommand(AllowConcurrentExecutions = true)] instead of [RelayCommand]

[GuidoNeele]

Tracked this issue down to the Loaded event not getting triggered, resulting in the taskCompletionSource not completing, which will keep the task running.

Maui/src/CommunityToolkit.Maui/Views/Popup/PopupExtensions.shared.cs

Lines 62 to 81 in 442f39e

	var taskCompletionSource = new TaskCompletionSource<object?>();
	async void handler(object? sender, EventArgs args)
	{
	page.GetCurrentPage().Loaded -= handler;
	try
	{
	var result = await CreateAndShowPopupAsync(page, popup, token);
	taskCompletionSource.TrySetResult(result);
	}
	catch (Exception ex)
	{
	taskCompletionSource.TrySetException(ex);
	}
	}
	page.GetCurrentPage().Loaded += handler;
	return taskCompletionSource.Task.WaitAsync(token);

Think this issue is caused by this fix dotnet/maui@21620dc which is included in 9.0.0-preview.5.24307.10 and 8.0.60

This is not an issue on Android. Didn't test on other platforms.

[GuidoNeele]

Issue is fixed if the Unload event is set too.

var taskCompletionSource = new TaskCompletionSource<object?>();

void unloadedHandler(object? sender, EventArgs args) => {};

async void loadedHandler(object? sender, EventArgs args)
{
	page.GetCurrentPage().Unloaded -= unloadedHandler;
	page.GetCurrentPage().Loaded -= loadedHandler;

	try
	{
		var result = await CreateAndShowPopupAsync(page, popup, token);

		taskCompletionSource.TrySetResult(result);
	}
	catch (Exception ex)
	{
		taskCompletionSource.TrySetException(ex);
	}
}

page.GetCurrentPage().Unloaded += unloadedHandler;
page.GetCurrentPage().Loaded += loadedHandler;

return taskCompletionSource.Task.WaitAsync(token);

[bijington]

Any chance the issue relates to this microsoft/microsoft-ui-xaml#1900

[PureWeen]

This fix should be available on the nightly feed as version 8.0.61-ci.net8.24319.3.

Can you test with the latest nightly build?
https://github.com/dotnet/maui/wiki/Nightly-Builds

[GuidoNeele]

Hi @PureWeen,

Just tried the nightly build and it indeed fixes the issue.
Thanks for the swift fix!