XOFF bug with copy mode

Hi,

With my DEC vt510, I have observed that when I hit C-u in copy 
mode (page up), it performs that action and then enters I-search 
mode uncommanded.  I-search mode is activated with C-s, which is 
also the XOFF character.

I have set "defflow on" in .screenrc, and have also verified via 
:info that the session is +flow.  However, screen seems to not be 
honoring XON/XOFF flow control while in copy mode.

Thanks,

John