By default, the drop-down list is long enough to contain eight items without requiring the user to scroll to see them all. To make the drop-down list smaller or larger, specify a number larger or smaller than eight as the DropDownCount value.  

If the DropDownCount value is larger than the number of items in the Items property, the drop-down list will be just large enough to hold all the possible choices and no more. If the DropDownCount value is smaller then the number of item in the Items property, the drop down list will display a scroll bar.  

JamControls.TJamOpenSaveComboBox