Item-Height
This property allows you to specify the height of the text area of the Combo-Box control. The unit of measure it’s inherited from the Lines property.
 
Example - Define a combo-box in screen section. The text area has a heigth of 2 lines while the list has heigth of 10 lines
screen section.
...
03 screen-1-co-1 Combo-Box
line 19.0
column 23.0
size 12.0 cells
lines 10.0
item-height 2.0
id 13
3-d
drop-down
.