--- a/browser/components/preferences/in-content/content.js
+++ b/browser/components/preferences/in-content/content.js
@@ -94,49 +94,50 @@ var gContentPane = {
 
   // FONTS
 
   /**
    * Populates the default font list in UI.
    */
   _rebuildFonts: function ()
   {
+    var preferences = document.getElementById("contentPreferences");
+    // Ensure preferences are "visible" to ensure bindings work.
+    preferences.hidden = false;
+    // Force flush:
+    preferences.clientHeight;
     var langGroupPref = document.getElementById("font.language.group");
     this._selectDefaultLanguageGroup(langGroupPref.value,
                                      this._readDefaultFontTypeForLanguage(langGroupPref.value) == "serif");
   },
 
   /**
    * 
    */
   _selectDefaultLanguageGroup: function (aLanguageGroup, aIsSerif)
   {
     const kFontNameFmtSerif         = "font.name.serif.%LANG%";
     const kFontNameFmtSansSerif     = "font.name.sans-serif.%LANG%";
     const kFontNameListFmtSerif     = "font.name-list.serif.%LANG%";
     const kFontNameListFmtSansSerif = "font.name-list.sans-serif.%LANG%";
     const kFontSizeFmtVariable      = "font.size.variable.%LANG%";
 
+    var preferences = document.getElementById("contentPreferences");
     var prefs = [{ format   : aIsSerif ? kFontNameFmtSerif : kFontNameFmtSansSerif,
                    type     : "fontname",
                    element  : "defaultFont",
                    fonttype : aIsSerif ? "serif" : "sans-serif" },
                  { format   : aIsSerif ? kFontNameListFmtSerif : kFontNameListFmtSansSerif,
                    type     : "unichar",
                    element  : null,
                    fonttype : aIsSerif ? "serif" : "sans-serif" },
                  { format   : kFontSizeFmtVariable,
                    type     : "int",
                    element  : "defaultFontSize",
                    fonttype : null }];
-    var preferences = document.getElementById("contentPreferences");
-    // Ensure preferences are "visible" to ensure bindings work.
-    preferences.hidden = false;
-    // Force flush:
-    preferences.clientHeight;
     for (var i = 0; i < prefs.length; ++i) {
       var preference = document.getElementById(prefs[i].format.replace(/%LANG%/, aLanguageGroup));
       if (!preference) {
         preference = document.createElement("preference");
         var name = prefs[i].format.replace(/%LANG%/, aLanguageGroup);
         preference.id = name;
         preference.setAttribute("name", name);
         preference.setAttribute("type", prefs[i].type);

--- a/browser/components/preferences/in-content/tests/browser.ini
+++ b/browser/components/preferences/in-content/tests/browser.ini
@@ -1,15 +1,16 @@
 [DEFAULT]
 skip-if = buildapp == "mulet"
 support-files =
   head.js
   privacypane_tests_perwindow.js
 
 [browser_advanced_update.js]
+[browser_basic_rebuild_fonts_test.js]
 [browser_bug410900.js]
 [browser_bug731866.js]
 [browser_bug795764_cachedisabled.js]
 [browser_bug1018066_resetScrollPosition.js]
 [browser_bug1020245_openPreferences_to_paneContent.js]
 [browser_change_app_handler.js]
 skip-if = os != "win" # This test tests the windows-specific app selection dialog, so can't run on non-Windows
 [browser_connection.js]

new file mode 100644
--- /dev/null
+++ b/browser/components/preferences/in-content/tests/browser_basic_rebuild_fonts_test.js
@@ -0,0 +1,26 @@
+Services.prefs.setBoolPref("browser.preferences.inContent", true);
+Services.prefs.setBoolPref("browser.preferences.instantApply", true);
+
+registerCleanupFunction(function() {
+  Services.prefs.clearUserPref("browser.preferences.inContent");
+  Services.prefs.clearUserPref("browser.preferences.instantApply");
+});
+
+add_task(function() {
+  yield openPreferencesViaOpenPreferencesAPI("paneContent", null, {leaveOpen: true});
+  let doc = gBrowser.contentDocument;
+  var langGroup = Services.prefs.getComplexValue("font.language.group", Ci.nsIPrefLocalizedString).data
+  is(doc.getElementById("font.language.group").value, langGroup,
+     "Language group should be set correctly.");
+
+  let defaultFontType = Services.prefs.getCharPref("font.default." + langGroup);
+  let fontFamily = Services.prefs.getCharPref("font.name." + defaultFontType + "." + langGroup);
+  let fontFamilyField = doc.getElementById("defaultFont");
+  is(fontFamilyField.value, fontFamily, "Font family should be set correctly.");
+
+  let defaultFontSize = Services.prefs.getIntPref("font.size.variable." + langGroup);
+  let fontSizeField = doc.getElementById("defaultFontSize");
+  is(fontSizeField.value, defaultFontSize, "Font size should be set correctly.");
+
+  gBrowser.removeCurrentTab();
+});