Show-Lines
When this style is set, items at the same level are connected by a line and, if they have children, a button is shown before their name. This just makes the Tree-View control more readable, without influencing its behavior. The lines may be shown also without this style using certain Look & Feel.
 
Example - Define a tree-view with show-lines style
... screen section. ...   03 screen-1-tv-1 Tree-View      line 2.7      column 3.4      size 20.8 cells       lines 29.1 cells       height-in-cells      color 144      id 2      show-lines      .  |