Add-on save-as-filename (reverses changes made in 18.0) no longer works in 20.0. can some repair it?

Question

In the FF 18 a change very annoying to me was made (once again, first was GUI in 4.0) to change way in which filenames was made.
GavinSharp from mozilla made fix on this fixed bug (no. 254139, which was no bug at all) in way of add-on named save-as-filename. This add-on in version 0.1, is still showed as active in version 20.0 but does not work.
Also Firefox 3 theme for firefox 4+ 2.0.0 now doesn´t work properly as button for download manager now only displays a blank space.
image can be found here: http://s23.postimg.org/lqpn87xbv/blank_space.png

Answer 1

I would like to add a little further information - in the earlier version I was able to create a text box for user input with:
var LYP = sym.$("LastYrPct");  //fourth layer - "LastYrPct"
LYP.html("Last Year Percent (enter as whole number i.e. 80 for 80%): ");
inputLYP = $('<input />').attr({ 'type': 'text' , 'value': '' , 'id': 'LYP' });
inputLYP.css('font-size', 9);
inputLYP.css('text-align', 'center');
inputLYP.appendTo(LYP);
And then later on the button submit function, read what the user had typed in the box with:
var lastYearP = inputLYP.attr("value");
... reading the "value" attribute I'd set up in the input box definition.  That no longer works and I'm assuming that it has something to do with the scope since the read happens in the submit button function, but I don't know.  I'm assuming I'm missing something obvious.  Thanks for giving me whatever help you can with this.