Image button coordinates not in form params

I have a form submitted using remote_form_tag. I have two image buttons
in this form.

I am accustomed in other languaes of detecting the presence or value of
buttonNameA.x and buttonNameB.x to know which button was clicked.

In the params I am getting from my form, I get entries for both buttons
with no indicators of which was clicked.

The output of essentially doing debug(params) simply shows
   btnSearch: ""
   btnClear: ""

What is Rails' solution to this? It seems to be eliminating rather
useful (and commonly used) info.

-- gw