Trim is, I think, one of the most used and most important features in any video editing software. As it stands, however, users of Shotcut have to learn the keyboard shortcuts (i/o) or have to go to a submenu of the timeline menu. IMHO, I think there should be icons in the timeline bar for trim left (i) and right (o), with a tooltip mentioning that they can press Ctrl/Cmd for ripple trimming.
There is enough space available in the timeline (icon) bar, and I’m pretty sure that there are more users who would use this than, say, scrubbing or markers.