end When click submit_tag "Cancel", the paramsi are:
{"button_identifier"=>"", "check_box2"=>"selected", "commit"=>"Cancel", "radio_button"=>"2 was selected", "action"=>"test_action", "controller"=>"index", "text_tag"=>"default_content", "text_area"=>"default_content", "password"=>"", "file"=>"", "select"=>"option2"}

    if params[:commit]  == "Cancel"
       render :text => "Clicked on Cancel"
    else
       render :text => "Clicked on Delete"
    end

****************
In form_tag, if you put multiple submit button, like
<%= submit_tag("Update", :name=>"submit"%>
<%= submit_tag("Delete", :name=>"submit"%>
The value of params[:submit] depends on which button you click, either
"Update" or "Delete". However, in form_remote_tag, no matter you click
which button, params[:submit] is always "Update".
Solution to this defect:
<%= hidden_field_tag "button_identifier" %>
<%= submit_tag("Update", :name=>"submit",:onclick=>"$
('button_identifier').value='Update'") %>
<%= submit_tag("Delete", :name=>"submit", :onclick=>"$
('button_identifier').value='Delete') %>