
How to copy and paste in Qubes
QubesOS provides a secure way to manage applications and file systems down to the hypervisor level, this provides greater separation and increased security as a result. To copy and paste between different qubes requires an additional step when both copying and pasting

Each Qubes has its own copy and paste board, for applications inside the same Qubes then copy and paste functions like any other operating system. The issue arises when copying and pasting between Qubes, as both are there own isolated instance and there is no universal paste board that can be shared between Qubes and maintain the systems hypervisor level security
Copying and pasting between Qubes requires an additional shift-ctrl-c after the initial ctrl-c (to add it to the local Qube paste board), the shift-ctrl-c will then copy the local paste board to the main paste board
To paste between Qubes, after copying the text from the source Qubes, the paste process requires shift-ctrl-v to be done before the ctrl-v. Where the shift-ctrl-v copies from the main paste board making it available locally to paste.
Command line pasting
The command line paste function doesn’t work through the standard shift-ctrl-v, as this shortcut is used during the pasting between Qubes process. The terminal paste function works the same as other qubes, so the paste board can get the data using shift-ctrl-v and to paste this into the command line this has to be done via the gui; edit > paste
Copying and pasting does take a couple of extra steps and this does interupt work flow, security comes at the cost of convenience. The extra step is intuitive and is a great example of the work arounds necessary to maintain a reasonable level of security offered by QubesOS
TLDR; How to copy and paste between Qubes in QubesOS, after copying with ctrl-v, then press shift-ctrl-v, and to paste into another Qubes press shift-ctrl-v, followed by the usual ctrl-v