Like merlight said, whatever
rowHeight you set for your row controls:
Lua Code:
ZO_ScrollList_AddDataType(scrollList, ROW_TYPE_ID, template, rowHeight, setupCallback, hideCallback, dataTypeSelectSound, resetControlCallback)
If the control height is actually larger than that rowHeight you set they will overlap. You may not have noticed it due to the resolution or even just the names that showed up in your list
(depending on how long they are) if the control was wide enough it would not need to wrap down to the next line. If the control was not wide enough then it would wrap to the next line and you would see the overlap.