really need help with scrolling

We're using 2.0.2.

The problem: we have combo boxes in our dataGrid but when the user scrolls the vertical scrollbar the state of the combo boxes are lost--reset to the original values.

I need to trap the scrolling event so I can save off the content of the combo boxes and restore them when scrolling is finished.

I've been thru this forum but not found anything that works.

to summarize:
I want to trap scroll events using prototype and DOM. Does anyone have an insight on how to do this? Not some two year old post that doesn't work: a snippet of code that will allow me to trap a vertical scrollbar in a datagrid.

thank you

The grid raises onScrollTopChanged and onScrollLeftChanged events -

grid.onScrollTopChanged = function(scrolltop){...}
grid.onScrollLeftChanged = function(scrollleft){...}

These are ActiveWidgets events and not related to DOM/Prototype.