I've seen elsewhere that scrolling via the mouse wheel (and other mousy events) can be enabled for tmux.. can this feature also be enabled in byobu (over tmux) and how?
Yes, this is possible. You just have to enter scrollback mode first.
Simply press F7, and then use your mouse scroll wheel. Finally, press ESC to exit scrollback mode.
It appears that some terminals won't allow you to scroll using your mouse still. For Gnome Terminal, untick the Scroll on keystroke option in the profile preferences (tab Scrolling).
If you still have this problem,
Try ALT + F12
In my case, this enables mouse scrolling on byobu
If you just want scrollback and you don't want to engage the tmux "mouse-mode" (which will interfere with your ability to cut-n-paste with the mouse) just add the following to .byobu/.tmux.conf
Now your terminal's scrollback works normally and you don't need to hit any special keys to engage the mouse. The drawback is that the terminal only knows about a single screen. You'll still need to use "mouse mouse" to scroll a screen other than the most recent (such as to get to a long-scrolling log buffer), but if you just want to scroll up to see what just scrolled off your screen, this will fix it! It doesn't know about split screens either. BTW, the "mouse mode" can be set automatically in your config files. You paste with your command key (usually CTRL-A) followed by the ] key. The mouse selection is cut automatically in mouse mode, but you'll have to get out of mouse mode or hold down SHIFT to get the usual clipboard behavior that allows you to paste into another GUI app.
Recommendation: Since byobu already uses multiple terminal sessions inside itself, you don't need to use it with multiple terminals. So, instead of having a hot-key that opens a new terminal, I assign my "open terminal" hot-key to tilda. Tilda drops-down from whatever workspace you are currently using (shows on all workspaces) and it stays running so it is always available. This works nicely with byobu because I now have 1 place for all my shell sessions (you can set tilda to run byobu instead of a normal shell and re-run it if you accidently exit your shell). Further, your terminal sessions out-last your GUI because you are using byobu. I log into my system with ssh and automatically get my byobu session (great to monitor compiles, etc) and the byobu virtual window resizes to my cell phone screen. When I reorient the phone, the byobu window on my desktop screen changes with the phone orientation - MAGIC! Very impressive to Windows users.
Next is to use enlightenment's terminal hacks to get a notification (from the GUI) when a terminal job finishes, but dbus permissions makes that iffy. If anyone gets this working with byobu please let me know!