[R-SIG-Mac] warning message from OS X

[Richard M. Heiberger]

May  6 15:08:33 rmhs-MacBook-Air.local R[21671] <Error>:
CGContextSetFont: invalid context 0x10064d430. This is a serious
error. This application, or a library it uses, is using an invalid
context  and is thereby contributing to an overall degradation of
system stability and reliability. This notice is a courtesy: please
fix this problem. It will become a fatal error in an upcoming update.

I get this message when I page up and down too quickly when using
the Quartz device.
I use the keyboard Apple-LeftArrow and Apple-RightArrow.

Rich