Bug 421814 - Use HITheme to draw backgrounds for groupboxes. Fix Thunderbirds preferences.css. r=philor.

mail/themes/pinstripe/mail/preferences/preferences.css

@@ -155,11 +155,8 @@ radio[pane=paneAdvanced]:active {
 }
 
 prefpane .groupbox-body {
-  border: none !important;
-  -moz-border-radius: 0px !important;
-  background-image: none !important;
+  -moz-appearance: none;
   padding: 8px 4px 4px 4px;
-
 }
 
 #paneTabs > groupbox {