I've inherited a legacy WinForms app that is full of horrible threading issues and cross-thread form updates. The developer has made use of Control.BeginInvoke to marshal the calls but has not been very successful with it. I think the original developer was a C programmer so their approach is very linear and imperative. I sympathize because I made a lot of the same mistakes 20+ years ago when C# first appeared.
I'm wondering if I replace these cross-thread control updates with MediatR notifications, would this marshal the handlers to the UI's STA thread, or will I still have to be concerned with thread marshaling?
I've solved this type of problem on other occasions using the Reactive Extensions, but I wonder whether MediatR would help in a more straightforward way inthis instance?
MediatR does not know anything about WinForms (or SynchronizationContexts in general). It's "just" a simple pattern to decouple commands/events and their handlers.
If you're using this in an app where synchronization is important (winforms/wpf), you will have to do the dispatching yourself. E.g. for winforms: use InvokeRequired/Invoke pattern to post things to the UI thread.