tmux: Remove code redundancy with hidden variable

.config/tmux/tmux.conf

@@ -189,10 +189,12 @@ set -g status-left "#{prefix_highlight}"
 
 set -g status-justify centre
 
+%hidden window_status='#{?window_zoomed_flag,#[underscore],}#I #W'
 set -g window-status-current-format \
-	"#[fg=#{@accent_color} bold]#{?window_zoomed_flag,#[underscore],}#I #W"
+	"#[fg=#{@accent_color} bold]"$window_status
 set -g window-status-format \
-	"#[fg=#{@ui_color}]#{?window_zoomed_flag,#[underscore],}#I #W"
+	"#[fg=#{@ui_color}]"$window_status
+setenv -ghu window_status
 
 # Create a key-table which self-inserts all keys that are bound in the root key
 # table. (C-h for example is sometimes needed as backspace sequence)