Description of problem: We allow users to manually signal an instance, even multiple instances at once. But there is no way to manually broadcast a signal - e.g. so that a start signal event may fire.
This is currently not planned for 6.0. Signals are typically used for triggers from external systems, not end users. If an end users should be able to start a process, a normal start event should be available (possibly in combination with a signal start event). Signal events can still be sent through the remote api.