Allow overscroll in the timeline panel
Currently the timeline panel stops vertically scrolling when the lowest layer reaches the bottom of the panel.
I'd like to suggest adding an option / preference to allow 'overscroll' in the timeline panel so that the lowest layer can be viewed above the bottom of the panel.
The primary reason for the request is that it gets a bit fiddly working on the lowest layers, and having the extra working space would make it more comfortable to interact with them.
In practice this could be very similar to the 'overscroll' option in Photoshop preferences (Preferences > Tools > Overscroll).
A secondary benefit would be that layers may 'jump' less when hiding keyframes.