Returns true, when this item has a visible checkbox in front to expand the subsequent branch
Shows or hides the checkbox for expanding the subsequent branch
Returns true if the [[TREE_CLASSES.SELECTED]] is attached to this item
Returns attaches or detaches the [[TREE_CLASS.SELECTED]] to this item
Extension of li-element that represents an object in a [[TreeList]] with a checkbox and a textinput as content. Additionally, may hold an instance of [[TreeList]] as branch to display children of the corresponding object.