Call a microflow from a custom widget with parent context

When calling a microflow from a mendix widget e.g. for an on change event on a text box the microflow can have multiple parameters, one for each parent dataview.

However this throws an error when the same setup is used with a custom widget. Perhaps it is easiest to explain with a screenshot.

here is a the page, as you can see it has two nested dataviews

And here is the microflow that has two parameters both of which are within the context

The microflow works fine for standard widgets but for custom widgets it throws an error 

Microflow should have one parameter of type TestDesignUI2.Container.

Can you make microflows for custom and mendix widgets have the same functionality in terms of parameters.