Back out changeset 7395f456cf4b (bug 594614) because it wasn't quite ready

browser/components/preferences/tabs.js

@@ -48,6 +48,9 @@ var gTabsPane = {
    *     1 opens such links in the most recent window or tab,
    *     2 opens such links in a new window,
    *     3 opens such links in a new tab
+   * browser.tabs.autoHide
+   * - true if the tab bar is hidden when only one tab is open, false to always
+   *   show it
    * browser.tabs.loadInBackground
    * - true if display should switch to a new tab which has been opened from a
    *   link, false if display shouldn't switch

browser/components/preferences/tabs.xul

@@ -57,6 +57,7 @@
 
     <preferences id="tabsPreferences">
       <preference id="browser.link.open_newwindow"     name="browser.link.open_newwindow"     type="int"/>
+      <preference id="browser.tabs.autoHide"           name="browser.tabs.autoHide"           type="bool" inverted="true"/>
       <preference id="browser.tabs.loadInBackground"   name="browser.tabs.loadInBackground"   type="bool" inverted="true"/>
       <preference id="browser.tabs.warnOnClose"        name="browser.tabs.warnOnClose"        type="bool"/>
       <preference id="browser.tabs.warnOnOpen"         name="browser.tabs.warnOnOpen"         type="bool"/>
@@ -81,6 +82,9 @@
       <checkbox id="warnOpenMany" label="&warnOpenManyTabs.label;"
                 accesskey="&warnOpenManyTabs.accesskey;"
                 preference="browser.tabs.warnOnOpen"/>
+      <checkbox id="showTabBar" label="&showTabBar.label;"
+                accesskey="&showTabBar.accesskey;"
+                preference="browser.tabs.autoHide"/>
       <checkbox id="switchToNewTabs" label="&switchToNewTabs.label;"
                 accesskey="&switchToNewTabs.accesskey;"
                 preference="browser.tabs.loadInBackground"/>

browser/locales/en-US/chrome/browser/preferences/tabs.dtd

@@ -7,6 +7,9 @@
 <!ENTITY warnOpenManyTabs.label       "Warn me when opening multiple tabs might slow down &brandShortName;">
 <!ENTITY warnOpenManyTabs.accesskey   "o">
 
+<!ENTITY showTabBar.label             "Always show the tab bar">
+<!ENTITY showTabBar.accesskey         "b">
+
 <!ENTITY switchToNewTabs.label        "When I open a link in a new tab, switch to it immediately">
 <!ENTITY switchToNewTabs.accesskey    "s">