Recovering From Stuck States:
The following FUNCTION commands should all be used with caution.

ESCAPE Helps you recover from stuck states such as "Output Hold" and "Sheet Lock"....

c-CLEAR INPUT
Clears window system locks. This is a last resort, although not as drastic as warm booting. Use this when none of the windows will talk to you, when you cannot get a System menu, and so on.

-- Genera Handbook