GUI toolkit question

[eguy at devio.us]

I'm building an app that operates on tuples (typically pairs) of
hierarchical structures, and i'd like to add a GUI to display my
internal representation of them, and simplify manipulations/operations
on them. My requirements are:

  1) Draw a single 3D representation of the hierarchies, and the
  connections between them.

  2) All objects must be interactive. That is, they should have
  left/middle/rightClick behavior; they must be draggable (with rubber
  band behavior of their conncections); the user should be able to
  highlight a set of them, associate them as a group, then execute
  some group operation.

  3) I don't need very fancy stuff from the normal widgets. Just
  menus, a few buttons, dialog boxes, etc.

  4) Don't need complex 3D behavior.

  5) Don't need to ever run on Windows, just *nix.

  6) May eventually need to either compile the Python, or port
  part/all of it to C++.

I started looking into Qt, Wx, Blender, etc, but don't even know if i
have the right questions in mind. Any thoughts, considerations,
recommendations would be much appreciated.

thanks in advance,
Eric