SolidColorBrush, bindings, and non-UI threads

[XenonAtom]

I want some code running in the background to be able to raise information to the window as basically a one-line log

<TextBlock Text="{Binding FeedbackText}" Foreground="{Binding FeedbackTextColor}" />

I had initially implemented this with FeedbackTextColor being a SolidColorBrush since the intellisense told me that Foreground should be an IBrush. This worked fine until the first time I updated it from a non-UI thread at which point I got "System.InvalidOperationException: Call from invalid thread".

Switching FeedbackTextColor from a SolidColorBrush to a string and using things like "#FF0000" instead of SolidColorBrush(Colors.Red) makes the error go away with no other code changes.

Why does creating a binding to a SolidColorBrush cause errors when I update the value outside of a UI thread as I would any other bound value? Are there other variable types that I need to watch out for and avoid using for bindings (or should I make sure to stick to just the basics - ints, strings, and the like)?

[LaurentInSeattle]

Updating the UI from a non-UI thread is a no-no-no...
You should use something like the code below.
Of note: Sometimes, rarely though, on Windows WPF, updating from a non-ui thread does work, usually when debugging.

Edit: Windows WPF

`

public static class Dispatch
{
// Sadly Action cannot be used as an extension method type...
public static void OnUiThread(Action action, DispatcherPriority priority = default)
{
if (Dispatcher.UIThread.CheckAccess())
{
// We are already on the UI thread, no need to invoke.
action();
}
else
{
Dispatcher.UIThread.Post(action, priority);
}
}

public static void OnUiThread<TArgs>(Action<TArgs> action, TArgs args, DispatcherPriority priority = default)
{
    if (Dispatcher.UIThread.CheckAccess())
    {
        // We are already on the UI thread, no need to invoke.
        action(args);
    }
    else
    {
        Dispatcher.UIThread.Post((Action)delegate { action(args); }, priority);
    }
}

}
`

[XenonAtom]

Yeah, I wasn't trying to update the UI directly. FeedbackTextColor is an ObservableProperty (from CommunityToolkit) which handles all the dispatching stuff. Apologies if that was unclear!

[maxkatz6]

SolidColorBrush is a UI object that maintains change listeners, that has to be created on UI thread.
ImmutableSolidColorBrush is an immutable version that can be created on any thread.