Tab-Border-Width
This property allows you to set or retrieve the width of the four borders of every tab in a Tab-Control control. The property is a list of four values that specify the width in pixels of the top, left, bottom and right border respectively. The border width is applicable only to Tab-Controls with the Tab-Flat style and without the Accordion style.
Setting the property to -1 resets the borders.
Passing less than four values assumes that the remaining values are 0.
This property overrides the layout provided by the iscobol.gui.native_style (boolean) * setting for the control.
 
Example - Define a tab-control control where every tab has a huge bottom border
screen section.
...
  03 screen-1-tb-1 Tab-Control
     line 2.8
     column 25.7
     size 34.6 cells 
     lines 28.9 cells 
     tab-border-width (1 1 5 1)
     id 19
     .