Some classes do not work well on Xaml Islands.

[azchohfi]

Describe the bug

Related to CommunityToolkit/Microsoft.Toolkit.Win32#228

There are a lot of issues when some controls and helpers of the toolkit run in the context of a Xaml Island. We need these fixed.

Steps to Reproduce

For example, try to use the ThemeListener class in a WPF app with Islands. It will throw exceptions.
Anything that leverages the Dispatcher using, for example CoreApplication.MainView.Dispatcher, will not work inside Xaml Islands since there is no such thing as a MainView. We need to refactor those to use the new DispatcherQueue.

Expected behavior

Should work in UWP and inside Xaml Islands (.Net Core).

Environment

NuGet Package(s): 6.0.0

Windows 10 Build Number:

• Fall Creators Update (16299)
• April 2018 Update (17134)
• October 2018 Update (17763)
• May 2019 Update (18362)
• Insider Build (build number: )

App min and target version:

• Fall Creators Update (16299)
• April 2018 Update (17134)
• October 2018 Update (17763)
• May 2019 Update (18362)
• Insider Build (xxxxx)

Device form factor:

• Desktop
• Xbox
• Surface Hub
• IoT

Visual Studio

• 2017 (version: )
• 2019 (version: )
• 2019 Preview (version: )

[ghost]

Hello azchohfi, thank you for opening an issue with us!

I have automatically added a "needs triage" label to help get things started. Our team will analyze and investigate the issue, and escalate it to the relevant team if possible. Other community members may also look into the issue and provide feedback 🙌