Hidden fields are not added to pricing total

I've got a custom total price calculation working after getting help from David Smith in this thread (thanks again):

http://forum.gravityhelp.com/topic/custom-total-price-calculation#post-18327

I would reply to the thread directly but it has been closed already.

His suggestion to use a User Defined field for my fee calculation works, but when it is hidden by setting the CSS to "display: none" as suggested in the last step it stops working. This seems due to the gformGetBasePrice function of gravityforms.js where there are two areas where there is a comment: "//If field is hidden by conditional logic, don't count it for the total"

If commented out the relevant code and it works fine now, but the whole point of this was not to touch the gravityforms.js so the form wouldn't get screwed up by Gravity Forms updates.

Is there any trick to hiding a pricing element and still having it count for the total without touching gravityforms.js?

David,

Thanks for reply and all your help so far, I'm learning a lot through this process.

I've tried this alternate way of hiding the field, but the results are the same. Even with this new way of hiding the field, unless those lines in the gravityforms.js are commented out, the total won't calculate.

Just one more strange thing that I noticed. Even with the lines commented out in my last post, the total doesn't work in Google Chrome (Firefox or IE are okay). I get the Javascript error "Uncaught SyntaxError: Unexpected token (" near the start of the price section of in gravityforms.js on this line:

function (element){
return element.parents('.gfield').css("display") == "none";
}

I just comment out that three line function (in addition to the other lines I mentioned in the last post) and the custom total works in Chrome. If I don't comment those three lines out the total doesn't work in Chrome. If works fine either way in Firefox and IE.

Strange isn't it?