Use onchange in threadPane and make selected color white.

mailnews/base/resources/content/threadPane.xul

@@ -36,7 +36,7 @@ Rights Reserved.
   xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul">
 
 
-<tree datasources="rdf:mailnewsfolders rdf:mailnewsmessages" id="threadTree" onclick="return parent.parent.LoadMessage(event.target.parentNode)" containment="http://home.netscape.com/NC-rdf#MessageChild">
+<tree datasources="rdf:mailnewsfolders rdf:mailnewsmessages" id="threadTree" onchange="return parent.parent.LoadMessage(event.target.parentNode)" containment="http://home.netscape.com/NC-rdf#MessageChild">
 
 
   <treecol style="width:47%" id="SubjectColumn" rdf:resource="http://home.netscape.com/NC-rdf#Subject"/>

mailnews/base/resources/skin/folderPane.css

@@ -35,6 +35,9 @@ tree {
 
 treeitem { 
  display: table-row; 
+ color: black;
+ font-family: Verdana;
+ font-size: 10pt;
 } 
 
 treehead { 
@@ -47,9 +50,6 @@ treebody {
 
 treecell { 
  display: table-cell; 
- color: black;
- font-family: Verdana;
- font-size: 10pt;
  white-space: nowrap;
 } 
 

mailnews/base/resources/skin/threadPane.css

@@ -36,6 +36,9 @@ tree {
 
 treeitem { 
  display: table-row; 
+ font-family: Verdana;
+ font-size: 10pt;
+ color: black;
 } 
 
 treehead { 
@@ -48,9 +51,6 @@ treebody {
 
 treecell { 
  display: table-cell; 
- color: black;
- font-family: Verdana;
- font-size: 10pt;
  white-space: nowrap;
 }