how to send the <esc> keystroke to a window?

[sven]

hi list,
i' want to remote control a program (dvgrab) which runs in 
interactive mode in a screen (-S program) session.
it's controlled by single keystrokes.
i'm doing it like that:
screen -S program -X register k c
screen -S program -X paste k
to send a 'c'
now how can i send the escape key just as if <esc> was pressed in that window?

thx,
sven.