Index: lib/sup/modes/thread-view-mode.rb
===================================================================
--- lib/sup/modes/thread-view-mode.rb	(revision 704)
+++ lib/sup/modes/thread-view-mode.rb	(working copy)
@@ -13,6 +13,15 @@
     attr_accessor :state
   end
 
+  HookManager.register "format-message-headers", <<EOS
+Format headers for a message in the detailed header display
+Variables:
+  message:  The message whose headers are to be formatted
+  dft_hdrs: An array of the headers that sup would display by default.
+Return value:
+  An array containing the headers to display.
+EOS
+
   DATE_FORMAT = "%B %e %Y %l:%M%P"
   INDENT_SPACES = 2 # how many spaces to indent child messages
 
@@ -466,8 +475,10 @@
         (parent ? "   In reply to: #{parent.from.mediumname}'s message of #{parent.date.strftime DATE_FORMAT}" : nil),
         show_labels.empty? ? nil : "   Labels: #{show_labels.join(', ')}",
       ].compact
-      
-      from + rest.map { |l| [[color, prefix + "  " + l]] }
+
+      hdrs = HookManager.run("format-message-headers", :message => m, :dft_hdrs => rest)
+      hdrs ||= rest
+      from + hdrs.map { |l| [[color, prefix + "  " + l]] }
     end
   end