django admin list_filter too long

I have a list_filter with loads of sectors. This list, on the right side of the page, is too long.

Can I use an input select field instead since I can't choose more than one sector?

I have seen this before, screenshots, but I can not find the way to do this.

edit:

I have a custom FilterSpec not a list_filter

This is how i resolved it (jQuery):

 $('#changelist-filter ul').each(function(){

        var maxlength = 10;

        if ($(this).children().length > maxlength )
        {
            var list=$(this),
                select=$(document.createElement('select')).insertBefore($(this).hide());

            $('>li a', this).each(function(){
                console.log($(this).parent().attr('class'));

                var target=$(this).attr('target'),
                    option=$(document.createElement('option'))
                        .appendTo(select)
                        .val(this.href)
                        .attr('selected', $(this).parent().attr('class'))
                        .html($(this).html())
                        .click(function(){
                            if (target==='_blank'){
                                window.open($(this).val());
                            }
                            else{
                                window.location.href=$(this).val();
                            }
                        });
            });
            list.remove();

        }
    });