[plt-scheme] text% `inner' width

Hi,

I'm trying to create a multi-column listbox that has a native look and 
feel. So I have the following questions:

1. How do I get the width of the area inside a text% editor, i.e. the 
width of the area that can be filled with embedded editors without 
causing the horizontal scrollbar to become activated?

  I've tried method get-width of the text% editor's editor-canvas%, but 
this returns the total width of the editor including the width of the 
vertical scrollbar. I need the `inner' width of the text area without 
scrollbar.

2. Is there any way to display listbox headers that look like they 
should on OS X? (Well,  I know how to copy the look from Aqua/Cocoa 
examples pixel by pixel, but I fear this would break anytime Apple 
decides to haul up their listbox design---which is going to happen 
sooner or later.)

Best regards,

Erich