The RegionGrowing tool does not seem to initialize the thresholds according to the values of the pixel neighborhoods of the selected seed-points.
System Specs:
OS X Yosemite 10.10.5
MITK Workbench 2016.3.99-c5b9d75a
ITK 4.9.0
VTK 7.0.0
Qt 5.6.1