So I tried to build such a widget myself.
I used a sprite with a DragDrop behavior attached set axes vertical only, pinned some other sprites on it to scroll with and added two sprites above and under with a blend mode set to source out to hide the scroll pan where you should not see it.
Better than words please look at the attached project to understand the trick I used.
There are still several problems :
- using the builtin DragDrop there is no momentum scrolling as you are used to see on touch devices
- scrolling doesn't end at the end of the pan
- having to add 2 sprites to hide content rather than 1 to make content visible is rather tedious. I dindn't find how to do the other way
- there is no scroll bar
I'd greatly appreciate comments on this and ideas on how to fix the above issues
Thanks a lot.