SrollablePositionedList: Need actions to scroll to (relative) offsets to implement pageup/pagedown

[allComputableThings]

Problem description

I'd like to connect key events to perform scrolling up and down in a SrollablePositionedList.
https://pub.dev/packages/scrollable_positioned_list

I can't use the provided method integer index values as the positions in this case because this list items may represent much larger than the smaller amount I might want to scroll when pressing an up or down arrow key.
For example, tapping the up/down arrow key might instruct the controller to go up/down 10% of the page (or some number of pixels).

What's missing: either:

• accessors to specify changes to the offsets in pixel positions (as a double), or
• change the index to a double, to allow positioning a fractional positions of a list item (this is less ideal as it leaves to users to determine how tall each list elements it).

Also see: #41

Perhaps exposing the front controller is enough?
#41 (comment)_