As FileMaker only has one main control used for both a list and a layout, the elastic scrolling is always there for you. But some users don't enjoy it in their layouts.
So just before the lunch today here at FileMaker Conference in Salzburg, I spend approximately 20 minutes on a new function to query and set the elasticity mode on the scrollbars in a layout:
MBS("Window.Scrollbar.SetScrollElasticity"; 0; "none")
You can set the scrollbars to auto, none and allowed. By default it is auto, so the system preferences define whether it is allowed or not. You can now switch it per layout and adjust it when switching to list mode or to layout mode.
PS: Coming soon in the next prerelease. If you like to try earlier, please email me.