I thought about how to design a live user interface while a program is running, and I decided to try making a magic lens
. A magic lens is a transparent window that you place on top of other windows to view or interact with in different ways. In the case of the Inertia designer, dubbed "X-Ray", when the window is over a view such as a button, clicking and dragging the mouse will move it.
Update: QuantumG has created a magic lens for Windows, cool!http://biodome.org/~qg/lens.html