A few months ago we posted a story about using TOPS with a Leica TC407, with a workaround for OSX users.
I wanted to go into more detail on the issue, and in short I will point any user working with TOPS on OSX to this document on the Python.org website, that will help you choosing the correct version of Python to use.
Do not use the pre-installed Python that comes with the OSX operating system.
Choose one of the recommended Python and Tcl/Tk installers, and of course let us know if you encounter difficulties. Remember that for the moment TOPS runs on Python 2, not Python 3. We are aware of the complications of the current setup, and we are looking into alternative user interfaces for our future versions.