code: function(ctx) {
  				var tree = ctx.tree;
  				tree.activeNode = null;
  				tree.focusNode = null;
  				tree.$div.find(">ul.fancytree-container").empty();
  				// TODO: call destructors and remove reference loops
  				tree.rootNode.children = null;
  			}
docs: Remove all nodes.
  @param {EventData} ctx