I thought this would be simple, but perhaps I’m thinking about it the wrong way. I would like to have the sign-up dialog/popup appear when a button on the page is clicked. I still want the sign-up button in the reusable site header to do the same.
However, I can’t seem to access that popup to set its state from the button on the page. Not sure how best to go about this. Any suggestions?
Got it! Just had to move the workflow from the Sign Up button to a custom event within the reusable element (header in this case) and then trigger that event from both buttons - i.e. the one in the header itself and the one on the page (which is not inside the header). You just have to use Trigger a custom event from a reusable element for the latter.
Anyway, having struggled through this, I now have a better understanding of reusable elements. I also have a suggestion…
I think the semantics would be much clearer if the aforementioned workflow action was called Trigger a custom event OF a reusable element instead of Trigger a custom event FROM a reusable element.
The latter says to me that the event will be “triggered from” a reusable element - i.e. the reusable element would initiate the trigger. It was only after spending a fair amount of time experimenting and reading the forums that its true meaning became evident. 
