title: JSTree Prevent drag from class
body: <p>Afternoon,
  I am having a few issues with JSTree 3.0. What I would like to do is on the load of the page prevent all nodes from being dragged using the dnd plugin. I then want to be able to click an edit button to enable the drag and drop functionality on all nodes. I think the best way to achieve this would be to set a class on all nodes and prevent the drag if it contains this class. When the edit is clicked the class is removed.</p>
  
  <p>I have found a way to get the class of the node on move_node using data.node.li_attr.class. This returns the class but I cannot work out how to stop the drag operation. Please see the below code so far:</p>
  
  <pre><code>$tree.on("move_node.jstree", function(e, data){
              var NodeClass = data.node.li_attr.class;
              if(NodeClass == "noMove")
              {
                  $.jstree.defaults.dnd_is_draggable(false);
              }else{
                  $tree.jstree("open_all");
                  var nodeId = data.node.id;
                  var nodeParent = data.parent;
                  var level = data.node.parents.length;
                  getChildren(data.node.id, level);
                  var url = window.location.origin + window.location.pathname.replace(regexp, "/ajaxSaveCaseFamily");
  
                  $.ajax({
                      type:"POST",
                      url:url,
                      data:{
                          "_token":token,
                          "nodeId":nodeId,
                          "nodeParent":nodeParent,
                          "depth":level
                      },
                      success:function(data){
                          var query = data;
                          if(query.RESULT == "FAIL"){
                              $("#errMsg").html(query.REASON);
                          }
                      }
                  })
              }
          });
  </code></pre>
  
  <p>Any help would be greatly appreciated!</p>
  
  <p>Thanks in advance!!</p>