iOS: Scrolling a native scroller via script problem

[Gerry]

I have a data grid that I'm scrolling in iOS using a native scroller.

I use this card script to scroll the data grid:

on scrollerDidScroll OffsetX, OffsetY
  if   iphoneControlTarget() = "listScroller" then
    set the vScroll of group "scroller" to OffsetY
  end if
end scrollerDidScroll

However, on opencard I manually scroll the scroller via script e.g.:

set the vScroll of group "scroller" to 2770

The problem is if the user then touches the scroller, the data grid
jumps to a vScroll of 0.

Anyone have an idea why?

Gerry