Softimage 2012 includes several examples of custom tools built with the new interactive tool SDK. For example, there’s the Box Transform Tool:
The Box Transform Tool is a complex manipulator-style tool that uses highlighting, shortcut keys, context menus and on-screen controls.
Interactive tools are a new type of custom plugin, implemented in C++. You need to know OpenGL, because it is used for drawing and picking in the viewport. More here…
The link is broken 😛