...And remove an unnecessary vbox while I'm here.

browser/components/prefwindow/content/pref-navigator.xul

@@ -43,8 +43,7 @@
   <!-- homepage specification -->
   <groupbox>
     <caption label="&header2.label;"/>
-    <vbox flex="1">
+    <hbox align="center" flex="1">
-      <hbox align="center">
       <label value="&location.label;" accesskey="&location.accesskey;" control="browserStartupHomepage"/>
       <textbox id="browserStartupHomepage" type="autocomplete" flex="1" 
                searchSessions="history" timeout="50" maxrows="6" preftype="localizedstring"
@@ -61,7 +60,6 @@
               id="browserUseBlank"
               prefstring="pref.browser.homepage.disable_button.blank_page"/>
     </hbox>
-    </vbox>
   </groupbox>
   <groupbox id="pref-nav-platform-extensions"/>
 </page>