text: jQuery(document).ready(function($){
  	$("#title").keyup(function() {
  		val = $(this).val();
  		if ( val == '' ) val = 'f(x)';
  		$(".sp-equation-variable").text( val + ' =' );
  	});
  
      $(".sp-equation-parts .button").draggable({
        appendTo: "body",
        helper: "clone",
        cursor: "move",
        distance: 10,
        containment: "#sp_equationdiv",
      }).click(function() {
      	$("<label class='button'></label>").text( $(this).text() ).append("<span class='remove'>&times;</span><input name='sp_equation[]' type='hidden' value='" + $(this).data("variable") + "'>").appendTo( $(".sp-equation-formula") );
      });
  
      $(".sp-equation").droppable({
        activeClass: "ui-state-active",
        hoverClass: "ui-state-hover",
        accept: ".button:not(.ui-sortable-helper)",
        drop: function( event, ui ) {
          $("<label class='button'></label>").text( ui.draggable.text() ).append("<span class='remove'>&times;</span><input name='sp_equation[]' type='hidden' value='" + ui.draggable.data("variable") + "'>").appendTo( $(".sp-equation-formula") );
        }
      }).sortable({
        items: ".button",
        tolerance: "pointer",
        containment: "#sp_equationdiv",
        sort: function() {
          $( this ).removeClass( "ui-state-active" );
        }
      });
  
      $(".sp-equation-formula").on("click", ".button .remove", function() {
      	$(this).closest(".button").remove();
      });
  });