@pichalite Ah, you're right. Looks like tpl_url was added in master. Changed the hook to contentLoaded, since end doesn't pass the template in 0.9.x.
Help: How to modify the register UI?
Now I start to write my plugin, and I have learned how to hook with "filter:register.build" and add some new input in the hook function, just by:
params.templateData.regFormEntry.push(phoneInput); // phoneInput is some html input element
It works well, but just add a new input in the "Registration Question" location, and I'd like to modify some about the Email Input, like the tip or check logic. So how can I do this? Thanks!