VTK-based annotation tool

I’m evaluating VTK as a framework for a python-based annotation tool. My goal is to use e.g. cubes to annotate 3D data.
Is this a viable option, do you have a better suggestion?
Is it possible to “drag” a corner or side of a cube and resize it along that dimension with a mouse?
How could can I get the world coordinates of the resulting rectangular cuboid?

VTK has some basic 3D interaction widgets, which may be usable if you just want to define very simple regions (see for example vtkBoxWidget). If you need anything more convenient and feature-rich then you can use Python embedded in applications, such as ParaView or 3D Slicer.