Improve and fix whatever issues found for the Stunner's Tree Explorer Widget.
Currently identified:

• Improve design & usability
  • UXD templates & errai UI
  • Improve tree margins, paddings
  • Replace UUID information on each item by some floating popup
  • Make item's name bigger / update location
  • Apply different styles for even/odd rows
  • Update cursor (pointer)
• Performance:
  • Avoid complete graph processing & re-painting on incremental updates
• Bugs
  • When the diagram has no canvas root, it seems that the nodes at root level do not appear on the tree explorer (basic-set)
  • Check and fix memory leaks, if any
• Unit testing