Hi Martin
Thanks for the input - keep the niggles coming. I'd suggest just posting
in this thread for the moment.
The Ctrl+Shift+C combination in gnome-terminal is a gnome shortcut,
which can be configured as normal in gnome. There's an alternative
(Ctrl+Insert) as qtpie pointed out.
The use of Ctrl+Shift+C in Qubes is Qubes specific, and can be configured
by editing /etc/qubes/guid.conf
This question has been raised before, and there are open issues at
github.com/qubesos/qubes-issues/issues
The greatest problem with proposed replacements is that they will almost
always conflict with shortcuts used by other users in specific programs.
There's been some discussion about this before and it doesn't seem
possible to find combinations that wont conflict *somewhere*.
For example your proposed use of Alt+Shift+C is used in i3 to reload
configuration.
So it's left to users to configure as suits them. (In general Qubes
policy is not to change stuff that ships with distro defaults.)
unman