GtkScrolledWindow: kinetic scroll should be cumulative
When using a touchpad 2-finger scroll gesture to initiate a kinetic scroll in Firefox, it is possible to accelerate the scroll speed by initiating that gesture again while the window is still scrolling. With each successive gesture the scrolling speed doubles, more or less.
This is a pretty important usability feature, especially when scrolling through very long pages. When considering that the default scroll speed is too high to be accurate or even comfortable (see #1308 (closed)) and might have to be lowered, this feature becomes even more important.
As of the current GTK versions (3.24.12 and master) this feature is not supported.
Soft-blocks #1308 (closed)