[Xy-pic] Latest XY Pic broken in Mac OS 10.6.7?

[Tom Reinhardt]

Up until late this week (15 April 2011), I had been happily using XY Pic on a variety of machines: two Linux (Ubuntu 10.4) boxes, a Windoze Box (MiKTeX) at work, and my iMac, running 10.6.7, at home. Sometime about the middle of the week I noticed that TeXShop complained about formatting diagrams with "double arrows," such as the standard monomorphism, such as:

\xymatrix{A\ar@<0.5ex>[r]^{f}\ar@<-0.5ex>[r]_{g} &B\ar[r]^{h} & C}

Specifically, it complained about an extra "}" after the \next @ (it seemed to me that it was focussing on the arrow specification containing the second "@<loc>" specification.

Have you seen this before? Has anyone else noticed this problem this week?

I confirmed that the code works fine on MiKTeX (Windoze) and on TeXLive (Linux); it's just on the Mac.

Naturally, I thank any kind soul for any advice/suggestions.

Regards,

Tom R