Zsh selects a pasted text

If you select text with simple drag, it goes into what I usually call the 'soft' buffer - you can paste it with a simple middle mouse click, but the moment you select anything else it's gone.

On the other hand, gnome and KDE and other WMs generally also let copy selected text into a 'hard' buffer where it stays until you explicitly copy something else into it.

Programs like Firefox don't so much maintain the Xorg selection as that they add a selection mode of their own that just happens to coincide with it -- for example, if you select text in firefox, then select something in another window, then go back to FF and middle click to paste, you'll get the latter text.

Use the following tmux.conf with copy-pipe in the new versions of tmux (1.8+):

set -g mouse on
# To copy:
bind-key -n -t emacs-copy M-w copy-pipe "xclip -i -sel p -f | xclip -i -sel c "

# To paste:
bind-key -n C-y run "xclip -o | tmux load-buffer - ; tmux paste-buffer"

1. prefix+[ into copy-mode
2. select content with mouse(hold)
3. M-w to copy that part into system clipboard
4. C-y the paste it inside tmux, C-v to paste it inside other regular application like web browser.