Due to the change in Tmux2.1,
I need to remap my mouse's middle click to tmux's paste:

```
bind -T root MouseDown2Pane run -b "tmux paste-buffer"

```

However, I also would like to enable using `Ctrl`
(or `Alt`, `Cmd`) + middle click
to paste the system's clipboard.

This is what I have tried (failed) so far:

```
bind -T root M+MouseDown2Pane run -b "pbpaste | tmux load-buffer -; tmux paste-buffer"

```