TM is very sensitive about order in which Alt and mouse button are released. I often end up with regular selection when I try to select columns.
I've checked XCode and Word - both requre Alt to be pressed only when clicking mouse button, not when relasing. I find that much easier to work with - it's fail-safe and I don't have to hold Alt when selecting.
Is there a reason why TM has selection implemented like this? Can this be changed or made configurable?