# invisible separators
set-option -g pane-border-fg black
set-option -g pane-border-bg black
set-option -g pane-active-border-fg black
set-option -g pane-active-border-bg black
becomes
set -g pane-border-style bg=black,fg=black
set -g pane-active-border-style bg=black,fg=black
as mentioned in the changelog.
