Thread Local variable inheritance or ExecutionContext fork event
It has always been frustrating to me that there is not only no way to propagate a user-defined thread-local variable from one thread to another (or, if I understand .NET concepts correctly, from one thread in an ExecutionContext to another thread in the same ExecutionContext or a copy of it).
This missing feature prevents one from using the Ambient Service Pattern properly:
Not only is there no thread-creation event, no feature to propagate thread-local variables from parent threads to child threads, and no way to associate user-defined data with an ExecutionContext, but also the BCL doesn't provide a property like Thread.ManagedParentThreadId that would help developers associate the child thread with the parent in some way.
Please add at least one of these features.