Restricting the particular node to drag and drop

Actually,we have a node and i want that particular node not to drag from the tree to the grid.when user tries to drag that we need to give a alert there any particular method for that???

Use the next:

tree.attachEvent("onBeforeDrag", function(sId){ if (sId=="specificID") { dhtmlx.message( { text:"You can't move this node", type:"alert" }); return false } });