




The generic function 
simple-pane-visible-width
 returns the width in pixels of the visible part of 
pane
, that is the width of the viewport, not including any borders or scroll bars. If 
pane
 is not displayed the function returns 
nil
.
See the CAPI User Guide for a description of the visible size of a pane.
CAPI Reference Manual - 15 Dec 2011