Add C-<Space> C-t binding for shell popup

tmux.conf

@@ -62,6 +62,9 @@ set -ga terminal-overrides 'xterm*:smxx=\E[9m'
 if -b '[ "`uname`" = "Darwin" ]' \
   'set -g default-command "reattach-to-user-namespace -l $SHELL"'
 
+# Open a popup with running the default shell
+bind C-t display-popup -d '#{pane_current_path}' -E '$SHELL'
+
 # Restore old next/previous window bindings
 bind C-n next-window
 bind C-p previous-window