+(defcustom wl-summary-flag-alist
+ '((important "orange"))
+ "An alist to define the flags for the summary mode.
+Each element is a form like:
+\(SYMBOL-OF-FLAG COLOR\)
+Example:
+\((important \"orange\"\)
+ \(todo \"red\"\)
+ \(business \"green\"\)
+ \(private \"blue\"\)\)"
+ :type '(repeat (list (symbol :tag "flag")
+ (string :tag "color")))
+ :group 'wl-summary)
+