A simple Draw(0 or a Browser opening might cause a Segmentation violation in TASImage::InitVisual () on Mac.
The configure command should specify explicitly where ROOT should find all X11-related libs
./configure --with-x11-libdir=/opt/local/lib/
--with-xpm-libdir=/opt/local/lib/
--with-xft-libdir=/opt/local/lib/
--with-xext-libdir=/opt/local/lib/