As per my understanding :- The renderer will check for each tree node when the tree is to be displayed. Depanding on your code it will check the information for that node and display accordingly. SO the renderer will go to all leaf nodes as well as parent nodes. U can write appropriate code by checking nodelevel and using node.getParent for checking the parent properties.
Setting the display properties for child nodes while displaying the parent doesnt make sense atleast as long as u r following the Renderer way.