using old pure C, I was able to define a custom windows message. Once done, it was possible to broadcast the message across my application. Any object, with defined listener was able to receive and process the message. OK, right now, I need to do the same in C#. I have a class (let’s call it ABC), which should broadcast a message in case something happens. The application has multiple forms (some of the are active, some of them not - that’s why I need general broadcast message/event instead of call a specific method). In case, something happens (e.g. ABC finishes some calculation), I want ABC to send a broadcast message (by broadcast I mean, the ABC class doesn’t know, who will receive it). The message will be processed by all active forms with defined listener. Please, could you let me know, how to send the message and how to define the listeners?