Does anyone have problem upgrading existing GTK2 to GTK2 2.10.6?

My MacBook Pro has GTK2 (2.10.2_1) installed via macports and I'm trying to upgrade to GTK2 2.10.6_0 (the latest as of this writing).

I'm getting the following error:

configure: error:

                *** Cannot link to Accessibility Toolkit. Accessibility Toolkit is required

                *** to build GTK+

Warning: the following items did not execute (for gtk2): com.apple.destroot com.apple.configure com.apple.build

DEBUG: Registry error: XFree86 not registered as installed.

    invoked from within

"registry_installed ${portname}"

    invoked from within

"$workername eval registry_installed \${portname}"

Error: Unable to upgrade port: 1

What is Accessbility Toolkit and where do I get it? And why do I suddenly get this error when I was able to install GTK2 previously?

Thanks for your help.