PanedWindow
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 Implements a paned widnow widget using primitive widgets as the
 building blocks.  The PanedWindow creates the top and bottom frames,
 and the pane itself.  The user may use the top and bottom methods to
 retrieve these frames and add children to them as needed.

 The base logic of this class is from a post to comp.lang.tcl from
 Jay Schmidgall.  I added additional features and made it a class.

   PUBLIC ATTRIBUTES:

     -fraction ...... initial percentage of sash
     -low ........... minimum percentage of sash
     -high .......... maximum percentage of sash
     -width ......... width of displayed list in characters
     -height ........ height of displayed list in lines

   METHODS:

     config ....... used to change public attributes
     top .......... return the top pane
     bottom ....... return the bottom pane

   USAGE:

     PanedWindow .pw -fraction .6 -width 600 -height 300 -high .8 -low .2
     set top [.pw top]
     set bot [.pw bottom]

     button $top.b1 -text "Hello"
     pack $top.b1 -fill both -expand yes -padx 10 -pady 10
     button $bot.b2 -text "World"
     pack $bot.b2 -fill both -expand yes -padx 10 -pady 10
     pack .pw -fill both -expand yes 
     wm minsize . 0 0
  
   X11 OPTION DATABASE ATTRIBUTES

     ...and the rest of the usual widget attributes

   ACKNOWLEDGEMENTS:
     James Noble - 1993
     Jay Schmidgall - 1994

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   AUTHOR:  Mark L. Ulferts          Phone: (214) 519-3947
            DSC Communications Corp  E-mail: mulferts@spd.dsccc.com
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