try to detect sanity check abnormalities (caused by Firebug)

errors.php

@@ -26,4 +26,7 @@
 
 	$ERRORS[10] = __("Your version of MySQL is not currently supported. Please see 
 		official site for more information.");
+
+	$ERRORS[11] = __("Sanity check request received twice. You could be running
+		Firebug or some other disrupting extension. Please turn it off.");
 ?>

prefs.js

@@ -14,6 +14,8 @@ var init_params = new Array();
 
 var caller_subop = false;
 
+var sanity_check_done = false;
+
 function expand_feed_callback() {
 	if (xmlhttp.readyState == 4) {
 		try {	
@@ -1239,7 +1241,13 @@ function backend_sanity_check_callback() {
 	if (xmlhttp.readyState == 4) {
 
 		try {
-		
+
+			if (sanity_check_done) {
+				fatalError(11, "Sanity check request received twice. You could be running"+
+			      " Firebug or some other disrupting extension. Please turn it off.");
+				return;
+			}
+
 			if (!xmlhttp.responseXML) {
 				fatalError(3, "[D001, Received reply is not XML]: " + xmlhttp.responseText);
 				return;
@@ -1275,6 +1283,8 @@ function backend_sanity_check_callback() {
 				}
 			}
 
+			sanity_check_done = true;
+
 			init_second_stage();
 
 		} catch (e) {

tt-rss.js

@@ -14,6 +14,7 @@ var cookie_lifetime = 0;
 var active_feed_id = 0;
 var active_feed_is_cat = false;
 var number_of_feeds = 0;
+var sanity_check_done = false;
 
 var xmlhttp = Ajax.getTransport();
 var xmlhttp_ctr = Ajax.getTransport();
@@ -88,7 +89,13 @@ function backend_sanity_check_callback() {
 	if (xmlhttp.readyState == 4) {
 
 		try {
-		
+	
+			if (sanity_check_done) {
+				fatalError(11, "Sanity check request received twice. You could be running"+
+			      " Firebug or some other disrupting extension. Please turn it off.");
+				return;
+			}
+
 			if (!xmlhttp.responseXML) {
 				fatalError(3, "[D001, Received reply is not XML]: " + xmlhttp.responseText);
 				return;
@@ -124,6 +131,8 @@ function backend_sanity_check_callback() {
 				}
 			}
 
+			sanity_check_done = true;
+
 			init_second_stage();
 
 		} catch (e) {