... Some comments and questions if I may:
The "+" button to quickly maximize a panel is fantastic. I am often looking at complex visualizations that should really be full-screen and it was always too much trouble to "drag" them to full screen and back.
Is the Spotter still a part of GToolkit? If not then what replaces it? (I can see that it is present in the image but Shift-Return doesn't seem to invoke it when the GTInspector window has focus.)
Is it still possible to pan left-right between "miller columns"? I see the squares at the top representing panes but clicking and dragging them doesn't seem to do anything.
How come a double-click is now needed to inspect an object? Is single-click going to have a new function?
Once more - great work you guys are doing !