cell flags, convert to use an int with flags marking 256 or RGB colours
in the top byte (except in cells, which we don't want to make any
bigger). From Brad Town.
options with a single foo-style option. For example:
set -g status-fg yellow
set -g status-bg red
set -g status-attr blink
Becomes:
set -g status-style fg=yellow,bg=red,blink
The -a flag to set can be used to add to rather than replace a style. So:
set -g status-bg red
Becomes:
set -ag status-style bg=red
Currently this is fully backwards compatible (all *-{fg,bg,attr} options
remain) but the plan is to deprecate them over time.
From Tiago Cunha.