Detecting system theme changes on platforms

[PhantomGamers]

Windows

On Windows you can subscribe to Microsoft.Win32.SystemEvents.UserPreferenceChanged from https://www.nuget.org/packages/Microsoft.Win32.SystemEvents/ as long as your app is targeting .net 5 or higher.

See https://github.com/PhantomGamers/SFP/blob/ead9c6f3765adbfb3574934bdbbea7c2facbc0fd/SFP_UI/Views/MainWindow.axaml.cs#L93-L109= for an example

Linux

On Linux, similar to how FluentAvalonia uses gsettings get org.gnome.desktop.interface gtk-theme to detect the theme, we can launch a process that runs gsettings monitor org.gnome.desktop.interface gtk-theme to determine when that changes.

See https://github.com/PhantomGamers/SFP/blob/f3e6c0114ce079c7a13d1eeb355666e4c26474eb/SFP_UI/Models/ThemeChangeDetection/Linux.cs for an example of this

OSX

Now this I'm not sure about. Is there an easy way to monitor for defaults settings changes on OSX? Looking online it doesn't seem like defaults has a monitor argument like gsettings does.