Backout ba704d0b0b09 (Bug 1023339) because there was a much better way to pull this off.

browser/components/preferences/in-content/advanced.xul

@@ -359,7 +359,7 @@
 #ifdef MOZ_UPDATER
       <groupbox id="updateApp" align="start">
         <caption><label>&updateApp.label;</label></caption>
-        <radiogroup id="updateRadioGroup" align="start"
+        <radiogroup id="updateRadioGroup"
                     oncommand="gAdvancedPane.updateWritePrefs();">
 #ifdef XP_WIN
 #ifdef MOZ_METRO

browser/components/preferences/in-content/privacy.xul

@@ -151,37 +151,28 @@
     <vbox id="historyCustomPane">
       <separator class="thin"/>
       <vbox class="indent">
-        <hbox>
-          <checkbox id="privateBrowsingAutoStart"
-                    label="&privateBrowsingPermanent2.label;"
-                    accesskey="&privateBrowsingPermanent2.accesskey;"
-                    preference="browser.privatebrowsing.autostart"
-                    oncommand="gPrivacyPane.updateAutostart()"/>
-          <spacer flex="1"/>
-        </hbox>
+        <checkbox id="privateBrowsingAutoStart"
+                  label="&privateBrowsingPermanent2.label;"
+                  accesskey="&privateBrowsingPermanent2.accesskey;"
+                  preference="browser.privatebrowsing.autostart"
+                  oncommand="gPrivacyPane.updateAutostart()"/>
+
         <vbox class="indent">
-          <hbox>
-            <checkbox id="rememberHistory"
-                      label="&rememberHistory2.label;"
-                      accesskey="&rememberHistory2.accesskey;"
-                      preference="places.history.enabled"/>
-            <spacer flex="1"/>
-          </hbox>
-          <hbox>
-            <checkbox id="rememberForms"
-                      label="&rememberSearchForm.label;"
-                      accesskey="&rememberSearchForm.accesskey;"
-                      preference="browser.formfill.enable"/>
-            <spacer flex="1"/>
-          </hbox>
+          <checkbox id="rememberHistory"
+                    label="&rememberHistory2.label;"
+                    accesskey="&rememberHistory2.accesskey;"
+                    preference="places.history.enabled"/>
+          <checkbox id="rememberForms"
+                    label="&rememberSearchForm.label;"
+                    accesskey="&rememberSearchForm.accesskey;"
+                    preference="browser.formfill.enable"/>
 
           <hbox id="cookiesBox">
-            <checkbox id="acceptCookies" label="&acceptCookies.label;"
+            <checkbox id="acceptCookies" label="&acceptCookies.label;" flex="1"
                       preference="network.cookie.cookieBehavior"
                       accesskey="&acceptCookies.accesskey;"
                       onsyncfrompreference="return gPrivacyPane.readAcceptCookies();"
                       onsynctopreference="return gPrivacyPane.writeAcceptCookies();"/>
-            <spacer flex="1"/>
             <button id="cookieExceptions" oncommand="gPrivacyPane.showCookieExceptions();"
                     label="&cookieExceptions.label;" accesskey="&cookieExceptions.accesskey;"
                     preference="pref.privacy.disable_button.cookie_exceptions"/>
@@ -223,11 +214,10 @@
           </hbox>
           <hbox id="clearDataBox"
                 align="center">
-            <checkbox id="alwaysClear"
+            <checkbox id="alwaysClear" flex="1"
                       preference="privacy.sanitize.sanitizeOnShutdown"
                       label="&clearOnClose.label;"
                       accesskey="&clearOnClose.accesskey;"/>
-            <spacer flex="1"/>
             <button id="clearDataSettings" label="&clearOnCloseSettings.label;"
                     accesskey="&clearOnCloseSettings.accesskey;"
                     oncommand="gPrivacyPane.showClearPrivateDataSettings();"/>

browser/components/preferences/in-content/sync.xul

@@ -276,7 +276,7 @@
     <groupbox id="syncOptions">
       <caption><label>&syncBrand.shortName.label;</label></caption>
       <hbox id="fxaSyncEngines">
-        <vbox align="start">
+        <vbox>
           <checkbox label="&engine.tabs.label;"
                     accesskey="&engine.tabs.accesskey;"
                     preference="engine.tabs"/>