Add new method to return topmost data element.
Add getter for ROIController
Fix type errors
Add selection mode support, remove label support
Load ROIToolboxView with the main controller initialization
Fix typo
Impl method
Slight redesign
Extend ROIController API. Impl many of the controller's methods
First simple impl of binary mask conversion methods
Impl ROI2BinMask in ROIController
Add nil check
Add default impl for asBinaryMask