tmux: make window list overflow markers more visible
tmux: make window list overflow markers more visible

By default, the `status-format' option is set as follows:

    $ tmux show-options -g status-format
    status-format[0] "#[align=left range=left #{status-left-style}]#[push-default]#{T;=/#{status-left-length}:status-left}#[pop-default]#[norange default]#[list=on align=#{status-justify}]#[list=left-marker]<#[list=right-marker]>#[list=on]#{W:#[range=window|#{window_index} #{window-status-style}#{?#{&&:#{window_last_flag},#{!=:#{window-status-last-style},default}}, #{window-status-last-style},}#{?#{&&:#{window_bell_flag},#{!=:#{window-status-bell-style},default}}, #{window-status-bell-style},#{?#{&&:#{||:#{window_activity_flag},#{window_silence_flag}},#{!=:#{window-status-activity-style},default}}, #{window-status-activity-style},}}]#[push-default]#{T:window-status-format}#[pop-default]#[norange default]#{?window_end_flag,,#{window-status-separator}},#[range=window|#{window_index} list=focus #{?#{!=:#{window-status-current-style},default},#{window-status-current-style},#{window-status-style}}#{?#{&&:#{window_last_flag},#{!=:#{window-status-last-style},default}}, #{window-status-last-style},}#{?#{&&:#{window_bell_flag},#{!=:#{window-status-bell-style},default}}, #{window-status-bell-style},#{?#{&&:#{||:#{window_activity_flag},#{window_silence_flag}},#{!=:#{window-status-activity-style},default}}, #{window-status-activity-style},}}]#[push-default]#{T:window-status-current-format}#[pop-default]#[norange list=on default]#{?window_end_flag,,#{window-status-separator}}}#[nolist align=right range=right #{status-right-style}]#[push-default]#{T;=/#{status-right-length}:status-right}#[pop-default]#[norange default]"
    status-format[1] "#[align=centre]#{P:#{?pane_active,#[reverse],}#{pane_index}[#{pane_width}x#{pane_height}]#[default] }"

The `list=left-marker` and `list=right-marker` commands create the
markings for the left and right overflow indicators if the window list
is too big to fit into the current status bar size. By default these are
"<" and ">", as seen above.

The trouble with our previous configuration was that the foreground
color was black (with a black background), inhibiting these markers from
showing up.

listx/syscfg,listx/syscfg,listx/syscfg,listx/syscfg,listx/syscfg