Please consider integration of https://github.com/MITK/MITK/pull/211
Makes gizmo (direct manipulation object in module Gizmo) track the mouse and highlight parts of the gizmo when under mouse.
Even if the gizmo is currently not available in MITK master, its functionality can be used by any custom view/application.
Anybody interested to see how the object can be used, see https://github.com/iwegner/MITK/commit/e5461f280915eb1291826c2b033ff646f17b3b20