Clipping text

[Brandon Lewis <brandon_lewis berkeley edu>]

I need to be able to control how wide text objecs are to prevent them from 
protruding past the edges of objects. I'm working on a fairly complicated user 
interface for the PiTiVi video editor which uses goocanvas. Here's a recent 
screenshot:

http://bp2.blogger.com/_0j8m-AnSlU8/SIQHGx-BB-I/AAAAAAAAAB8/DWH3g_PpWUc/s1600-h/new_layout.png

I am having trouble understanding how to use the clip-path property on an 
object. Essentially I want to be able to clip the text label's length to the 
width of the rectangular background. Setting the clip at all seems to do nothing 
or make object completely invisible, depending on the values I am using.

Are the clip-path coordinates relative to the object or to the canvas?