var http_request = false;


        function block_dropdown( dropdown ) {
                block_field( "step_1", dropdown.obj.name )
        }
        function release_dropdown( dropdown ) {
                release_field( "step_1", dropdown.obj.name )
        }


        function changeYear( dropdown ) {

                var year=dropdown[dropdown.selectedIndex].value
                var submit_btn=document.getElementById('submit_btn');
                var submit_btn = document.getElementById('submit_btn');

                block_dropdown( model_dropdown )
                block_dropdown( style_dropdown )
                submit_btn.disabled=1;
                submit_btn.className="go_to_step2";


                if ( year ) {

                        document.body.style.cursor = 'wait';

                        http_request = getHTTPObject();
                        http_request.open( "POST", "../ajax.php?xml=make", true );
                        http_request.onreadystatechange = updateMakes;
                        http_request.setRequestHeader( "Content-Type","application/x-www-form-urlencoded" );
                        http_request.send( "year="+year );

                } else {

                        block_dropdown( make_dropdown )
                }
        }



        /**
         * Update "Make" dropdown when makes info was received
         */
        function updateMakes() {

                if (http_request.readyState != 4 || http_request.status != 200) return;


                var xmldoc = http_request.responseXML;
                var makes = xmldoc.getElementsByTagName('value');
                make_dropdown.del_all();
//                if (makes.length>1) 
make_dropdown.add( "", "Select A Make" );
                for ( var z=0; z<makes.length; z++ ) {
                        var make = makes[z].firstChild.data
                        make_dropdown.add( make, make );
                }
                make_dropdown.update();

                release_dropdown( make_dropdown )
                document.body.style.cursor = 'default'
        }


        // ----


        /**
         * Request list of models
         */
        function changeMake( dropdown ) {

                var form = document.step_1;

                var year=form.year[form.year.selectedIndex].value
                var make=form.make[form.make.selectedIndex].value
                var submit_btn = document.getElementById('submit_btn');

                block_dropdown( style_dropdown )
                submit_btn.disabled=1;
                submit_btn.className="go_to_step2";

                if ( year && make ) {

                        document.body.style.cursor = 'wait'
                        http_request = getHTTPObject()
                        http_request.open( "POST", "../ajax.php?xml=model", true )
                        http_request.onreadystatechange = updateModels
                        http_request.setRequestHeader( "Content-Type","application/x-www-form-urlencoded" )
                        http_request.send( "make="+make+"&year="+year )

                } else {

                        block_dropdown( model_dropdown )
                }
        }


        /**
         * Update "Model" dropdown when model info was received
         */
        function updateModels() {

                if (http_request.readyState != 4 || http_request.status != 200) return;

                var xmldoc = http_request.responseXML;
                var models = xmldoc.getElementsByTagName('value');
                model_dropdown.del_all();
//                if (models.length>1) model_dropdown.add( "", "Select A Model" );
                model_dropdown.add( "", "Select A Model" );
                for ( var z=0; z<models.length; z++ ) {
                        var model = models[z].firstChild.data
                        model_dropdown.add( model, model );
                }
                model_dropdown.update();

                release_dropdown( model_dropdown )
                document.body.style.cursor = 'default'

        }


        // ----


        /**
         * Request list of styles
         */
        function changeModel() {
                var form = document.step_1;

                var year=form.year[form.year.selectedIndex].value
                var make=form.make[form.make.selectedIndex].value
                var model=form.model[form.model.selectedIndex].value
                var submit_btn = document.getElementById('submit_btn')

                submit_btn.disabled=1;
                submit_btn.className="go_to_step2";

                if ( year && make && model ) {

                        document.body.style.cursor = 'wait'

                        http_request = getHTTPObject()
                        http_request.open( "POST", "../ajax.php?xml=style", true )
                        http_request.onreadystatechange = updateStyles
                        http_request.setRequestHeader( "Content-Type","application/x-www-form-urlencoded" )
                        http_request.send( "year="+year+"&make="+make+"&model="+model )
                }
        }


        /**
         * Update "Style" dropdown when styles was received
         */
        function updateStyles() {

                if (http_request.readyState != 4 || http_request.status != 200) return

                var xmldoc = http_request.responseXML
                var styles = xmldoc.getElementsByTagName('value')
                style_dropdown.del_all()
                style_dropdown.add( "", "Select A Style" )
                if (!styles.length) style_dropdown.add( "-1", "-" )
                for ( var z=0; z<styles.length; z++ ) {
                        var style = styles[z].firstChild.data
                        style_dropdown.add( style, style )
                }
                style_dropdown.update()

                release_dropdown( style_dropdown )
                document.body.style.cursor = 'default'
        }



        function changeStyle( dropdown ) {

                var style=dropdown[dropdown.selectedIndex].value
                var submit_btn = document.getElementById('submit_btn');
                if ( style )
                {
                        submit_btn.disabled = 0;
                        submit_btn.className="go_to_step2_a";
                }
                else
                {
                        submit_btn.disabled = 1;
                        submit_btn.className="go_to_step2";
                }
        }