TabBox:

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   Create a tab box from plug-ins.
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   Form:
   [x, y, tag] = TabBox( action, modifier, tabs, content, position, hFig, 
                 formatInfo, data, callback)

   modifier is passed to the content functions as their action
   units are defined externally. When a contents function is called
   action is used as the function name and modifier as the action.
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   Inputs
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   action         (1,:)    Action to be taken
   modifier       (1,:)    Modifier to the action
   tabs           {n}      Cell array with tab labels
   content        {n}      Cell array with function names that define
                           the content
   position       (1,4)    [left,bottom,width,height] content region only!
   hFig           (1,1)    Figure handle 
   formatInfo     (1,1)    Data structure with format information
                           .FontAngle       (1,:)
                           .FontName        (1,:)
                           .FontSize        (1,1)
                           .FontUnits       (1,1)
                           .FontWeight      (1,:)
                           .ForegroundColor (1,3)
   data           {}       Initialization data
   callback       (1,:)    CreateCallback function when a control in a panel is hit

   -------
   Outputs
   -------
   x              {}      Tags for panels
   y              {}      Handles to tab buttons
   tag            {}      Tag for the frame around the tab box. Userdata of this
                          frame provides access to all of the parts of the tab box

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