Sadly this still leaves you with a rather crippled subset of the real thing. I.e. "copy mode" instead of proper scrolling, no native text selection, and very noticeable latency and glitches.
It's the price you pay for emulating a 35 years old piece of hardware[1] inside an emulator of the same...
On a random note, why do all unix applications (generalising I know) seem to default to a super-minimal set of options? Surely the kind of people who get annoyed by mouse integration (and you can just ignore it) are the kind of people who can find out how to turn it on, whereas those of us who are using tmux for the first time want all the nice options turned on by default?
It's the price you pay for emulating a 35 years old piece of hardware[1] inside an emulator of the same...
[1] http://en.wikipedia.org/wiki/VT100