Horizontal
When this style is set, the slider bar is displayed from left to right. The Lines property controls the height and the Size property controls the width.
Without this style instead the slider bar is displayed from top to bottom. The Lines property controls the width and the Size property controls the height.
 
Example - Define a horizontal slide-bar
screen section.
...
  03 screen-1-sl-2 Slider
     line 39.1
     column 12.8
     size 38.4 cells 
     lines 3.8 cells 
     id 10
     horizontal
     show-labels
     min-val 10
     max-val 100
     page-size 5
     labels-increment 15
     .