First of all, docs are incorrect. It says: "fires before showing the form with the new data; receives as Parameter the id of the constructed form. beforeShowForm : function(formid) {…}". In reality, it receives a jQuery object of the form.

Secondly, not always. The first time it runs, the form does not exist yet - so the object is empty. Only as from the second run it really points to the form. Which is inconsistent, I think. Can the code be adjusted so that at the time of running beforeShowForm the form always existed?