Is it possible to have combo box with check box for a SELECT search field?

DONE!!!
// used some java script jquery.min.js and jquery.multiple.select.js and multiple-select.css
<link rel=”stylesheet” href=”/wordpress/wp-content/themes/sydney/login/multiple-select.css” />
//After $returnvar .= “</select>”;
//Add
$returnvar .= ‘<script src=”/wordpress/wp-content/themes/sydney/js/jquery.min.js”></script>
<script src=”/wordpress/wp-content/themes/sydney/js/jquery.multiple.select.js”></script>
<script>

$(function() {
$(“#’.str_replace(‘/’, ”, $name).’”).change(function() {
console.log($(this).val());
}).multipleSelect({
width: “100%”
});
});
</script>’;

For Full code..its here..
Add this new function in class-search-filter-generate-input.php file

public function generate_multiselectcheckbox($dropdata, $name, $defaults, $elem_attr = "",$id="",$all_items_label=null)

    {
        $returnvar = "";

//        if($additionalFeature==false){
//            $returnvar .= '<div style="display:none;" id="div_' . str_replace('/', '', $name) . '">';
//        }
//        else{
//            $returnvar .= '<div style="" id="div_' . str_replace('/', '', $name) . '">';
//        }

        $returnvar .= '<select multiple="multiple" class="postform" name="'.$name.'[]"'.$elem_attr.'id="'.str_replace('/', "", $name).'" slug="'.$all_items_label.'">';
        if(isset($all_items_label))
        {

            if($all_items_label=="")
            {//check to see if all items has been registered in field then use this label
                $returnvar .= '<option selected="selected" class="level-0" value="'.$name.'">'.esc_html($all_items_label).'</option>';
            }
        }
        foreach($dropdata as $dropdown)
        {
            $selected = "";

            if(isset($defaults))
            {
                if(is_array($defaults)) //there should never be more than 1 default in a select, if there are then don't set any, user is obviously searching multiple values, in the case of a select this must be "all"
                {
                    foreach($defaults as $defaultid)
                    {
                        if($defaultid==$dropdown->term_id)
                        {
                            $selected = ' selected="selected"';
                        }
                    }
                }
            }
            $returnvar .= '<option class="level-0" value="'.esc_attr($dropdown->term_id).'"'.$selected.'>'.esc_html($dropdown->cat_name).'</option>';
        }
        $returnvar .= "</select>";

        $returnvar .= '<script src="/wordpress/wp-content/themes/sydney/js/jquery.min.js"></script>
                       <script src="/wordpress/wp-content/themes/sydney/js/jquery.multiple.select.js"></script>
                        <script>
                        $(function() {
                            $("#'.str_replace('/', "", $name).'").change(function() {
                            console.log($(this).val());
                            }).multipleSelect({
                            width: "100%"
                            });
                        });
                        </script>';

        return $returnvar;
    }

choose from the UI which choice_type u want. for example. I choose multi select so Call this function into
if ($values['choice_input_type'] == "multiselect") by referring

$returnvar .= $this->create_input->generate_multiselectcheckbox($countrychildren, $field_name, $defaults, $elem_attr, str_replace('/', '', $field_name), false);

Don’t forget to add the above javascript files and css file.

Keep calm and enjoy coding.. 😉
Cheerssss