When scrolling to the edge of a window the layout will scroll over the edge of the window and snap back, like in OS X.
This behavior is okay in List-View because it is a normal interaction to scroll there.
In Form-View we most likely only scroll in portals and if you miss it, or if the portal has come to its last record, scrolling of the layout will take over instead of scrolling the portal. Which is really confusing, because if you have the exact amount of references, as the portal rows and you have set the option to hide scrollbar, then you need to scroll, if you want to "check" the portal. In that case you are automatically at the portals last record, so layout scrolling will take over and the window floats away.
Please give us the option to set this Scroll Elasticity for Form View!