I have installed ActiveTcl8.6.1.1.297588-macosx10.5-i386-x86_64-threaded on my OS X 10.9.1 . However, when I launch IDLE by running idle3 from the
ActiveTcl8.6.1.1.297588-macosx10.5-i386-x86_64-threaded
idle3
I faced the same problem. You can solve this by downloading the Active Tcl 8.5.17 version rather than the lastest version.