Hi again. I've prepared a patch for three other skins to distinguish visited threads from unvisited threads. I'm hoping the differences are perceivable enough, and the contrast against the background is sufficient.

Index: skins/ardoise/css.txt
==================================================================
--- skins/ardoise/css.txt
+++ skins/ardoise/css.txt
@@ -887,10 +887,13 @@
 .fileage td:first-child,
 .sortable td:first-child,
 .userTable td:first-child {
   border-left: transparent
 }
+.fileage a:visited {
+  color: rgb(72, 144, 224);
+}
 table.label-value th {
   vertical-align: middle
 }
 .brlist table td {
   padding: 5px

Index: skins/eagle/css.txt
==================================================================
--- skins/eagle/css.txt
+++ skins/eagle/css.txt
@@ -406,6 +406,10 @@
   font-family: "courier new";
 }
 
+.fileage a:visited {
+  color: rgba(176,176,176,1.0);
+}
+
 div.filetreeline:hover {
   background-color: #7EA2D9;
 }

Index: skins/xekri/css.txt
==================================================================
--- skins/xekri/css.txt
+++ skins/xekri/css.txt
@@ -385,10 +385,17 @@
 
 .fileage tr:hover {
   background-color: #225;
 }
 
+.fileage a {
+  color: #60c0ff;
+}
+
+.fileage a:visited {
+  color: #40a0ff;
+}
 
 /**************************************
  * File List : Tree
  */
 

I hope these help out, but feel free to tweak as needed.

Cheers, brickviking

(Post 14)