diff --git a/addons/web/static/src/js/chrome.js b/addons/web/static/src/js/chrome.js
index 38923d268cf..484c58ef2c4 100644
--- a/addons/web/static/src/js/chrome.js
+++ b/addons/web/static/src/js/chrome.js
@@ -195,10 +195,20 @@ openerp.web.Loading =  openerp.web.Widget.extend(/** @lends openerp.web.Loading#
     init: function(parent, element_id) {
         this._super(parent, element_id);
         this.count = 0;
+        this.blocked_ui = false;
         this.session.on_rpc_request.add_first(this.on_rpc_event, 1);
         this.session.on_rpc_response.add_last(this.on_rpc_event, -1);
     },
     on_rpc_event : function(increment) {
+        var self = this;
+        if (!this.count && increment === 1) {
+            // Block UI after 3s
+            this.long_running_timer = setTimeout(function () {
+                self.blocked_ui = true;
+                $.blockUI();
+            }, 3000);
+        }
+
         this.count += increment;
         if (this.count) {
             //this.$element.html(QWeb.render("Loading", {}));
@@ -206,6 +216,12 @@ openerp.web.Loading =  openerp.web.Widget.extend(/** @lends openerp.web.Loading#
             this.$element.show();
             this.widget_parent.$element.addClass('loading');
         } else {
+            clearTimeout(this.long_running_timer);
+            // Don't unblock if blocked by somebody else
+            if (self.blocked_ui) {
+                this.blocked_ui = false;
+                $.unblockUI();
+            }
             this.$element.fadeOut();
             this.widget_parent.$element.removeClass('loading');
         }