diff --git a/chrome/content/zotero/overlay.js b/chrome/content/zotero/overlay.js
index 6018de8637..0bf8266745 100644
--- a/chrome/content/zotero/overlay.js
+++ b/chrome/content/zotero/overlay.js
@@ -50,14 +50,14 @@ var ZoteroOverlay = new function()
 		showInPref = Components.classes["@mozilla.org/preferences-service;1"]
 							.getService(Components.interfaces.nsIPrefService)
 							.getBranch('extensions.zotero.').getIntPref('showIn');
-		this.isTab = showInPref === 2;
+		this.isTab = showInPref !== 1;
 		if(!isFx36) {
 			var observerService = Components.classes["@mozilla.org/observer-service;1"]
 				.getService(Components.interfaces.nsIObserverService);
 			var zoteroObserver = function(subject, topic, data) {
 				if(subject != window) return;
 				observerService.removeObserver(this, "browser-delayed-startup-finished");
-				if(showInPref === 2) {
+				if(showInPref === 3) {
 					var tabbar = document.getElementById("TabsToolbar");
 					if(tabbar && window.getComputedStyle(tabbar).display !== "none") {
 						// load Zotero as a tab, if it isn't loading by default
@@ -314,7 +314,7 @@ var ZoteroOverlay = new function()
 		// If no existing tab, add a new tab
 		if(!tab) tab = gBrowser.addTab(ZOTERO_TAB_URL);
 		// Pin tab
-		if(!isFx36) gBrowser.pinTab(tab);
+		if(!isFx36 && showInPref == 3) gBrowser.pinTab(tab);
 		// If requested, activate tab
 		if(!background) gBrowser.selectedTab = tab;
 	}
diff --git a/chrome/content/zotero/preferences/preferences.js b/chrome/content/zotero/preferences/preferences.js
index 15391e4dd6..5b276a33a9 100644
--- a/chrome/content/zotero/preferences/preferences.js
+++ b/chrome/content/zotero/preferences/preferences.js
@@ -73,6 +73,11 @@ function init()
 	} else if(document.location.hash == "#cite") {
 		document.getElementById('zotero-prefs').showPane(document.getElementById("zotero-prefpane-cite"));
 	}
+	
+	var showInAppTab;
+	if(!Zotero.isFx4 && (showInAppTab = document.getElementById("zotero-prefpane-general-showIn-appTab"))) {
+		showInAppTab.setAttribute("hidden", "true");
+	}
 }
 
 
@@ -1791,6 +1796,7 @@ function updateProxyPrefs() {
 		document.getElementById('zotero-proxies-autoRecognize').disabled = 
 		document.getElementById('zotero-proxies-disableByDomain-checkbox').disabled = 
 		document.getElementById('zotero-proxies-disableByDomain-textbox').disabled = !transparent;
+
 }
 
 /**
@@ -1810,8 +1816,9 @@ function updateWordProcessorInstructions() {
  */
 function handleShowInPreferenceChange() {
 	var showInSeparateTab = document.getElementById("zotero-prefpane-general-showIn-separateTab");
+	var showInAppTab = document.getElementById("zotero-prefpane-general-showIn-appTab");
 	if(Zotero.isFx4) {
-		if(showInSeparateTab.selected) {
+		if(showInAppTab.selected) {
 			document.getElementById('statusBarIcon').selectedItem = document.getElementById('statusBarIcon-none');
 			Zotero.Prefs.set("statusBarIcon", 0);
 		} else if(Zotero.isFx4) {
diff --git a/chrome/content/zotero/preferences/preferences_firefox.xul b/chrome/content/zotero/preferences/preferences_firefox.xul
index 9089690edc..23c66a406a 100644
--- a/chrome/content/zotero/preferences/preferences_firefox.xul
+++ b/chrome/content/zotero/preferences/preferences_firefox.xul
@@ -59,6 +59,7 @@ To add a new preference:
 							<radiogroup id="showIn" orient="horizontal" preference="pref-showIn" oncommand="handleShowInPreferenceChange()">
 								<radio id="zotero-prefpane-general-showIn-browserPane" label="&zotero.preferences.showIn.browserPane;" value="1"/>
 								<radio id="zotero-prefpane-general-showIn-separateTab" label="&zotero.preferences.showIn.separateTab;" value="2"/>
+								<radio id="zotero-prefpane-general-showIn-appTab" label="&zotero.preferences.showIn.appTab;" value="3"/>
 							</radiogroup>
 						</row>
 						<row position="2" id="zotero-prefpane-general-statusBarIcon-row">
diff --git a/chrome/content/zotero/tab.js b/chrome/content/zotero/tab.js
index 10b5e9e513..a1c10df4bd 100644
--- a/chrome/content/zotero/tab.js
+++ b/chrome/content/zotero/tab.js
@@ -104,7 +104,7 @@ var ZoteroTab = new function()
 			if(tabs.length > 1) {
 				window.close();
 			} else {
-				if(Zotero.isFx4) this.containerWindow.gBrowser.unpinTab(tabs[0]);
+				if(Zotero.isFx4 && tabs[0].pinned) this.containerWindow.gBrowser.unpinTab(tabs[0]);
 				document.location.replace(this.containerWindow.gHomeButton.getHomePage());
 			}
 			return;
diff --git a/chrome/locale/en-US/zotero/preferences.dtd b/chrome/locale/en-US/zotero/preferences.dtd
index 083e1afe3b..7632683baa 100644
--- a/chrome/locale/en-US/zotero/preferences.dtd
+++ b/chrome/locale/en-US/zotero/preferences.dtd
@@ -10,6 +10,7 @@
 <!ENTITY zotero.preferences.showIn						"Load Zotero in:">
 <!ENTITY zotero.preferences.showIn.browserPane					"Browser pane">
 <!ENTITY zotero.preferences.showIn.separateTab					"Separate tab">
+<!ENTITY zotero.preferences.showIn.appTab					"App tab">
 <!ENTITY zotero.preferences.statusBarIcon				"Status bar icon:">
 <!ENTITY zotero.preferences.statusBarIcon.none			"None">
 <!ENTITY zotero.preferences.fontSize						"Font size:">