Currently, time-scale compression/expansion is via these arrow icons:

which is fine as far as it goes. It would be great to get the mouse-wheel into the act

I suggest that when the Ctrl button is held down, the mouse wheel have the same effect as the arrow icons.
Also, if the end of the horizontal scroll bar could be grabbed and dragged, that's a good interface for time-scale compression/expansion too.
It's understood that these are fine touches for luxury driving ...