In 2.79, it was easy to set the start and end values of the timeline with the S and E shortcuts.:
If I put my green cursor at frame 42 and press S it sets the Start value at 42:
It would be great to have them re-implemented in 2.9, but before asking in the Right Click Select website I wanted to make sure that I wasn't missing something, for example, is it shortcutable in the Preferences?
(By the way, it would also be great if Dope Sheet and Timeline were merged into one unique window but it's another topic...)