Width-In-Cells
This style implies that the value specified for the Size property, the one setting the Tree-View control’s width, is expressed in CELLS. It is possible to get the same result writing: "Size value CELLS".
 
Example - Define a tree-view with width-in-cells
...
screen section.
...
  03 screen-1-tv-1 Tree-View
     line 2.7
     column 3.4
     size 20.8
     lines 29.1 cells 
     height-in-cells
     color 144
     id 2
     show-sel-always
     show-lines
     width-in-cells
     .