Toolbar actions are rendered into `lino_XXX.js` and therefore they currently cannot have parameters. They work only when rendered as action links (i.e. dynamically when the target row is known).  

Or to be more precise: they *can* be in the toolbar, but Lino does not initialize their parameter fields dynamically. :meth:`lino.core.actions.Action.action_param_defaults` is never called.

For example :attr:`.pcsw.Client.create_visit` has a dialog box which does not need to get initialized dynamically.