The vDos nag is displayed once every 3 hours, but only if operated networked.
You would mean version 2014.10.19, the vDos project started in 2012 and went public in 2013. Some key combinations got meanwhile reserved by Windows itself. I don’t recall you consulted me for the 15 characters copy limitation, it is simply not there in vDos.
Best to install the latest vDos version (2020.03.01) and consult its documentation for what key combinations can (still) be used.
So the cause of that Clipper 15 character limitation was already discussed in that post of February 2016. I tend to forget about resolved issues rather quickly.
I didn’t miss your point: Windows 10 reserved some extra key combinations for itself with the 2017 Fall Creators Update. Like Ctrl+Win+C/V for <Turn color filters on or off>/<Open shoulder taps>. So those key combinations don’t work as before in vDos.
As of version 2018.0501 it is: Win+Ctrl+left mouse click starts selecting a rectangle block of text. Drag the mouse and release the mouse button: The selected text is copied to the Window Clipboard. Win+Ctrl+right mouse click pastes the Windows Clipboard text. Win+Ctrl can be omitted if the DOS program doesn’t use the mouse, config.txt: no MOUSE = ON.