I have a perception that tab in panels can only tab across but not vertically. Am I correct?
If it can tab vertically, how can it be done or where is the reference material? How can I put some trace on the panels.

Unless the keymap is read from some network file (not usually done), individual desktops would need to be configured. If there is toi be a change to the mapping in general, new users would at least be properly configured when their systems were set up. Hopefully, there is already a newline mapped and all that will be necessary is to tell people how to use it.Mapping the keybroad will be a permanent change across all applications?