diff --git a/phpgwapi/js/jsapi/egw_debug.js b/phpgwapi/js/jsapi/egw_debug.js
index 8969391761..4133e91641 100644
--- a/phpgwapi/js/jsapi/egw_debug.js
+++ b/phpgwapi/js/jsapi/egw_debug.js
@@ -21,9 +21,157 @@ egw.extend('debug', egw.MODULE_GLOBAL, function(_app, _wnd) {
 	/**
 	 * DEBUGLEVEL specifies which messages are printed to the console.
 	 * Decrease the value of EGW_DEBUGLEVEL to get less messages.
+	 *
+	 * @type Number
+	 * 0 = off, no logging
+	 * 1 = only "error"
+	 * 2 = -- " -- plus "warning"
+	 * 3 = -- " -- plus "info"
+	 * 4 = -- " -- plus "log"
+	 * 5 = -- " -- plus a stacktrace
 	 */
 	var DEBUGLEVEL = 2;
 
+	/**
+	 * Log-level for local storage
+	 *
+	 * @type Number
+	 */
+	var LOCAL_LOG_LEVEL = 1;
+	/**
+	 * Number of log-entries stored on client, new errors overwrite old ones
+	 *
+	 * @type Number
+	 */
+	var MAX_LOGS = 1000;
+	/**
+	 * Number of last old log entry = next one to overwrite
+	 *
+	 * @type String
+	 */
+	var LASTLOG = 'lastLog';
+	/**
+	 * Prefix for key of log-message, message number gets appended to it
+	 *
+	 * @type String
+	 */
+	var LOG_PREFIX = 'log_';
+
+	/**
+	 * Log to clientside html5 localStorage
+	 *
+	 * @param {String} _level "navigation", "log", "info", "warn", "error"
+	 * @param {Array} _args arguments to egw.debug
+	 * @returns {Boolean} false if localStorage is NOT supported, null if level requires no logging, true if logged
+	 */
+	function log_on_client(_level, _args)
+	{
+		if (!window.localStorage) return false;
+
+		switch(_level)
+		{
+			case 'warn':
+				if (LOCAL_LOG_LEVEL < 2) return null;
+			case 'info':
+				if (LOCAL_LOG_LEVEL < 3) return null;
+			case 'log':
+				if (LOCAL_LOG_LEVEL < 4) return null;
+			default:
+				if (!LOCAL_LOG_LEVEL) return null;
+		}
+		var data = {
+			time: (new Date()).getTime(),
+			level: _level,
+			args: _args,
+		};
+		// Add in a trace, if no navigation _level
+		if (_level != 'navigation' && typeof (new Error).stack != 'undefined')
+		{
+			data.stack = (new Error).stack;
+		}
+		if (typeof window.localStorage[LASTLOG] == 'undefined')
+		{
+			window.localStorage[LASTLOG] = 0;
+		}
+		window.localStorage[LOG_PREFIX+window.localStorage[LASTLOG]] = JSON.stringify(data);
+
+		window.localStorage[LASTLOG] = (1 + parseInt(window.localStorage[LASTLOG])) % MAX_LOGS;
+	}
+
+	/**
+	 * Get log from localStorage with oldest message first
+	 *
+	 * @returns {Array} of Object with values for attributes level, message, trace
+	 */
+	function get_client_log()
+	{
+		var logs = [];
+
+		if (window.localStorage && typeof window.localStorage[LASTLOG] != 'undefined')
+		{
+			var lastlog = parseInt(window.localStorage[LASTLOG]);
+			for(var i=lastlog; i < MAX_LOGS && typeof window.localStorage[LOG_PREFIX+i] != 'undefined'; ++i)
+			{
+				logs.push(JSON.parse(window.localStorage[LOG_PREFIX+i]));
+			}
+			for (var i=0; i < lastlog; ++i)
+			{
+				logs.push(JSON.parse(window.localStorage[LOG_PREFIX+i]));
+			}
+		}
+		return logs;
+	}
+
+	/**
+	 * Clears whole client log
+	 */
+	function clear_client_log()
+	{
+		if (!window.localStorage) return false;
+
+		for(var i=0; i < MAX_LOGS; ++i)
+		{
+			if (typeof window.localStorage[LOG_PREFIX+i] != 'undefined')
+			{
+				delete window.localStorage[LOG_PREFIX+i];
+			}
+		}
+		delete window.localStorage[LASTLOG];
+
+		return true;
+	}
+
+	/**
+	 * Show user an error happend by displaying a clickable icon with tooltip of current error
+	 */
+	function raise_error()
+	{
+		var icon = jQuery('#topmenu_info_error');
+		if (!icon.length)
+		{
+			var icon = jQuery(egw(_wnd).image_element(egw.image('dialog_error')));
+			icon.addClass('topmenu_info_item').attr('id', 'topmenu_info_error');
+			// ToDo: tooltip
+			icon.on('click', egw(_wnd).show_log);
+			jQuery('#egw_fw_topmenu_info_items').append(icon);
+		}
+	}
+
+	// bind to global error handler
+	jQuery(_wnd).on('error', function(e)
+	{
+		log_on_client('error', [e.originalEvent.message]);
+		raise_error();
+		// rethrow error to let browser log and show it in usual way too
+		throw e;
+	});
+
+	/* show error icon / show_log trigger */
+	window.setTimeout(function(){
+		raise_error();
+	}, 10000);
+
+
 	/**
 	 * The debug function can be used to send a debug message to the
 	 * java script console. The first parameter specifies the debug
@@ -72,7 +220,25 @@ egw.extend('debug', egw.MODULE_GLOBAL, function(_app, _wnd) {
 					_wnd.console.error.apply(_wnd.console, args);
 				}
 			}
+			// raise errors to user
+			if (_level == "error") raise_error(args);
+
+			// log to html5 localStorage
+			if (typeof stack != 'undefined') args.pop();	// remove stacktrace again
+			log_on_client(_level, args);
+
+		},
+
+		/**
+		 * Display log to user because he clicked on icon showed by raise_error
+		 *
+		 * @returns {undefined}
+		 */
+		show_log: function()
+		{
+			alert('show_log clicked :-)');
+			if (_wnd.console) _wnd.console.log(get_client_log());
 		}
-	}
+	};
 });
 
diff --git a/phpgwapi/templates/idots/css/traditional.css b/phpgwapi/templates/idots/css/traditional.css
index 27f56a6b80..08f350370a 100755
--- a/phpgwapi/templates/idots/css/traditional.css
+++ b/phpgwapi/templates/idots/css/traditional.css
@@ -910,3 +910,11 @@ td.lettersearch {
 	font-weight: bold;
 	background-image: url(../../default/images/dialog_error.png);
 }
+
+/**
+ * Javascript error image / trigger for log
+ */
+#topmenu_info_error {
+	width: 16px;
+	cursor: pointer;
+}