dashboard autorefresh

refresh notebook list and cluster list when :
- page get focus
- every 60 sec when page is on focus

stop refreshing every 60 sec when page loose focus

IPython/frontend/html/notebook/static/js/projectdashboardmain.js

@@ -30,8 +30,41 b' $(document).ready(function () {'
     IPython.cluster_list = new IPython.ClusterList('div#cluster_list');
     IPython.login_widget = new IPython.LoginWidget('span#login_widget');
 
-    IPython.notebook_list.load_list();
-    IPython.cluster_list.load_list();
+    var interval_id=0;
+    // auto refresh every xx secondes, no need to be fast,
+    //  update is done at least when page get focus
+    var time_refresh = 60; // in sec
+
+    var enable_autorefresh = function(){
+        //refresh immediately , then start interval
+        IPython.notebook_list.load_list();
+        IPython.cluster_list.load_list();
+        if (!interval_id){
+            interval_id = setInterval(function(){
+                    IPython.notebook_list.load_list();
+                    IPython.cluster_list.load_list();
+                }, time_refresh*1000);
+            }
+    }
+
+    var disable_autorefresh = function(){
+        clearInterval(interval_id);
+        interval_id = 0;
+    }
+
+    // stop autorefresh when page lose focus
+    $(window).blur(function() {
+        disable_autorefresh();
+    })
+
+    //re-enable when page get focus back
+    $(window).focus(function() {
+        enable_autorefresh();
+    });
+
+    // finally start it, it will refresh immediately
+    enable_autorefresh();
+
     IPython.page.show();
     
     // bound the upload method to the on change of the file select list