EndDate to open calendar in the month selected by the StarDate attribute

Hello, I want to make an EndDate attribute in a NewEdit page to open its calendar in the month selected in the StarDate attribute. I think I have to use an xpath but I can not figure out where to apply it and what constrain it would be. Thanks in advance.
1 answers

There might be a technical trick somewhere; I would add a onchange nanoflow on the start date input widget.

This nanaoflow changes the context Object, set member endDate  to Object/StartDate. 

By doing so, the enddate equals the start date and thus when opening the datepicker, the startdate is already selected and thus in the same month :-D