Figure out where the Txul regression is on linux (bug 401949). a=mconnor

browser/themes/gnomestripe/browser/browser.css

@@ -1843,10 +1843,7 @@ toolbarbutton.bookmark-item[dragover="true"][open="true"] {
   cursor: help;
   background-color: ThreeDFace;
 %ifdef MOZ_WIDGET_GTK2
-  border: 1px solid ThreeDShadow;
-  -moz-border-start: none;
-  border-top: none;
-  border-bottom: none;
+  border-right: 1px solid #888;
 %else
   -moz-appearance: toolbox;
   outline: 1px solid ThreeDShadow;