primefaces - show p:modalPanel from java backing bean / controller class and update specific id or collection of id strings

here's how you show a p:modalPanel from a java backing bean call:
org.primefaces.context.RequestContext.getCurrentInstance().execute("myModalPanelWV.show()");

"modalPanelWV" is the widgetVar value, e.g.:
<p:modalPanel id="myModalPanel" widgetVar="myModalPanelWV" ...

update an id from backing bean:
org.primefaces.context.RequestContext.getCurrentInstance().update("growl");

OR update a Collection<String> of IDs:
org.primefaces.context.RequestContext.getCurrentInstance().update(myCollectionOfStringIds);