Same here. But I found a decent workaround.

I have following in my .tmux.conf:

   set -g history-limit 1000
   # See https://wiki.archlinux.org/index.php/Tmux#Scrolling_issues
   set -g terminal-overrides 'xterm*:smcup@:rmcup@'

Now I can scroll using "scroll bar" which is acceptable for me. Plus I also get native text-selection.