The way you add this is:
GLMBrowser>>gtInspectorOpenTreeIn: composite
<gtInspectorPresentationOrder: 30>
composite roassal
title: 'Tree';
painting: [:view :b |
b viewTreeOn: view ]
I also recently extended ROView with a simple display to show a simple tree of elements. This again can be useful when debugging the creation of views:
gtInspectorElementsHierarchyIn: composite
<gtInspectorPresentationOrder: 20>
composite tree
title: 'Elements';
display: [ :each | {each} ];
children: #elements
But, here is another thing. Because it is directly in the code of the object, you can even use the Methods editor for each object to extend the inspector from within the inspector while inspecting :). The UI is not yet what it should or could be, but it does create new possibilities. This is similar to what happens in Moose when during analysis we realize that we need a visualization, so we switch to an easel, write the visualization and continue the interaction with the objects directly there. This can be very powerful if done right.
Doru