Thread

<select>
{exp:weblog:categories site="default_site" weblog="gallery" style="linear" category_group="17"}
    <option value="{path=gallery}">{category_name}</option>
{/exp:weblog:categories}
</select>

<form id="filters">

<?php
//enable php/ee bridges
global $IN;
global $DB;

$last_segment = (! isset($IN->SEGS[sizeof($IN->SEGS)])) ? '0' : $IN->SEGS[sizeof($IN->SEGS)];
if(  $last_segment[0] == "P" ){
$last_segment = (! isset($IN->SEGS[sizeof($IN->SEGS)])) ? '0' : $IN->SEGS[sizeof($IN->SEGS)-1];
}

//get child categories 

//get category parents
$parent_categories = array("17", "18");
reset($parent_categories);

//loop each parent
foreach ($parent_categories as $key => $value) {

    //query the database
    $query = $DB->query("SELECT cat_id as category_id, cat_name AS category_name, cat_url_title AS category_url_title FROM exp_categories WHERE parent_id = '".$value."'");

    if ($query->num_rows > 0)
    {
        if ( $value == "17" ){ echo "<label>Pick a genre</label><select class='filter_category'><optgroup label='Genre'><option></option>"; }
        if ( $value == "18" ){ echo "<label><em>OR</em> material</label><select class='filter_category'><optgroup label='Material'><option></option>"; }
        
        //get each child category and add to, or remove from URL
        foreach($query->result as $row)
        {
            
        //get category url title
        $cat_url = $row['category_url_title'];
        $cat_name= $row['category_name'];

        $cat_selected = "";
        if( $last_segment == $cat_url ){
            $cat_selected = "selected";
        }else{
            $cat_selected = "";
        }

            echo "<option ". $cat_selected ." value='{homepage}gallery/category/" . $cat_url. "/'>" . $cat_name. "</option>";

        }
        echo "</optgroup></select>";
    }
}
?>


                <label><em>OR</em> <a href="http://{homepage}gallery/" title="View all">view all</a></label>

            </form>