between win/xp and cygwin? I think that is his intent.
Microsoft(which you know):
copy is by selecting then ctrl-c or menu-copy.
paste is by ctrl-v or menu-paste.
Motif & cygwin:
Selecting text would spontaneously
(some people might prefer the term, automatically)
copy into clipboard.
Paste is by middle button click.
e.g. copying from MS to Cyg:
copy text from MS win, move cursor to cyg window and press/release middle
button.
Conversely from cyg to MS:
select text at cyg win, move mouse to MS win and ctrl-v.
Voila!
However, if you don't have a middle mouse button, or you had mapped that
button to do something else, you could use -emulate3buttons option
which would require you to press both mouse buttons together to emulate
the middle button.