Array of node objects.
Array, default = 
This array contains all the node objects of the sidebar. Each node object may in turn contain other nodes thus allowing unlimited
nestedness. A node object has the structure defined in .node_template
You can define nodes during object creation:
You should not change nodes directly during run-time. If you do change them you will need to call .refresh()
method to update it on the screen (you might also need to set parent
properties of the nodes).
methods to change