Limiting Umenu's drop menu visible items.

Hi,

When there is a lot of items on a Umenu the drop menu size is limited by the amount of space from the Umenu to the farthest screen limit (top or bottom), so if there is no more space the drop menu can be cropped (and there appears atriangle at the end that indicates there are more items), or the drop menu splits in two, making two item's columns.

I wonder if there is some trick to limit de drop menu amount of visible items or to split it in two columns, besides of using a small resolution screen.

Thanks!