Comment 1 for bug 250359

The summary says that you cannot select text in the terminal window, but the
description says that you can. If you can select text, try to copy it with
Ctrl+Insert. This works for me in GNOME, so you may have success in KDE.

Ctrl+Insert is one of the old-school trio of:

    • Cut: Shift+Delete
    • Copy: Ctrl+Insert
    • Paste: Shift+Insert

I agree that Ctrl+Shift+C “ought” to work for consistency with the GNOME
Terminal emulator (and perhaps other programs), so if the above works for you,
you could maybe rework this bug report as a simple feature request. (Only
trivial feature requests are supposed to be tracked in Launchpad Bugs, so if
this is more than trivial, it would be better off in Launchpad Blueprints or
Ubuntu Brainstorm, for example!)

I’ll mark this bug as Incomplete till you have responded.