Passing parameters with signal events

Noticed that since 6.6.0 it should be possible to pass parameters with signal events:

“In and out parameters can be defined for signal events, similar to the existing in and out parameter support for call activities. By defining in parameters for a signal boundary event for example, variables can be set on the process instance scope from the signal payload data.”

Also found test cases in the source code that implements this behaviour. However it seems to be no support at all for this in the modeler? If I import one of the test processes into the modeler and then export it, then the extension elements with the parameter information is gone what it seems.

We store our processes in version control and are recording all changes to the processes this way. This means that it will be hardly impossible for to use this feature?

Is this something that will be implemented in the modeler?

Would it be possible to implement this behaviour by using script/service tasks instead? What methods are the corresponding in the RuntimeService? “void signalEventReceived(String signalName, Map<String, Object> processVariables);” seems promising, do I use that for throwing? Which should be used in for catching? runtimeService.trigger? But how do I specify the alertSignal name?