When I tried it, this feature made me feel very unsafe, in that a small, "unrelated" movement of the mouse could lead to huge modifications to my current desktop workspace (and snap me out of concentration at the very least).
Seems a feature that leads to surprise, a bit like if "i" worked as a toggle both in command mode and insert mode in vim.
I'll note that I'm not bashing the feature, nor a personal preference. I'd like to know what advantages are there, from a knowledgeable user.
> When I tried it, this feature made me feel very unsafe
I use it to switch between windows without having to fiddle with something like alt-shift, or clicking on the target window each time I want to move. It's about speed, not safety. Once you get used to it though, I don't think you end up in the wrong window very often.
By focus, do you mean automatically making the window containing the mouse the active one? It will send scroll events to whatever window the mouse is over, which I find really nice when I have two open, typing in one but reading from something else (like a PDF or web page). It saves me two clicks to not change focus just to scroll, but not let the other window take over. I guess it's all just a preference then.
As you said, scrolling under pointer is a huge boon, but also clicking on background windows (in most well-behaved apps) usually focuses the window without sending the click to the window (possibly triggering an unintended destructive action).
But the best part is that cmd-click allows interacting with windows without focusing them, allowing all sorts of things like translating your IM window out from under a movie player without covering the video.
I didn't know cmd+click. I can't think of a good use case in my world, but I'm pleased as punch that it exists, and that I've learned something new about OSX today.
That, is a different story. As I have the habit of moving out the cursor to an edge to keep the window clear when I type, I never use this in any WM settings.
