diff --git a/mozilla/calendar/base/content/calendar-task-view.js b/mozilla/calendar/base/content/calendar-task-view.js
index 111ad793628..aedc2d494df 100644
--- a/mozilla/calendar/base/content/calendar-task-view.js
+++ b/mozilla/calendar/base/content/calendar-task-view.js
@@ -186,6 +186,9 @@ function taskViewUpdate(filter) {
           return (percentCompleted(item) < 100) &&
                  !(item.dueDate.compare(now()) > 0);
         },
+        open: function filterCompleted(item) {
+            return (percentCompleted(item) < 100);
+        },
         completed: function filterCompleted(item) {
             return (percentCompleted(item) >= 100);
         }
diff --git a/mozilla/calendar/lightning/content/messenger-overlay-sidebar.xul b/mozilla/calendar/lightning/content/messenger-overlay-sidebar.xul
index 2fc5758532f..a5db2cb9d79 100644
--- a/mozilla/calendar/lightning/content/messenger-overlay-sidebar.xul
+++ b/mozilla/calendar/lightning/content/messenger-overlay-sidebar.xul
@@ -224,6 +224,14 @@
                    mode="task"
                    label="&calendar.task.filter.completed.label;"
                    accesskey="&calendar.task.filter.completed.accesskey;"/>
+         <menuitem id="tasks-view-filter-open"
+                   name="filtergroup"
+                   type="radio"
+                   value="open"
+                   command="calendar_task_filter_command"
+                   mode="task"
+                   label="&calendar.task.filter.open.label;"
+                   accesskey="&calendar.task.filter.open.accesskey;"/>
        </menupopup>
      </menu>
      <menuseparator id="before-Unifinder-Section" mode="calendar"/>
@@ -489,6 +497,7 @@
                  <radio id="opt_notstarted_filter" label="&calendar.task.filter.notstarted.label;" value="notstarted" command="calendar_task_filter_command"/>
                  <radio id="opt_overdue_filter" label="&calendar.task.filter.overdue.label;" value="overdue" command="calendar_task_filter_command"/>
                  <radio id="opt_completed_filter" label="&calendar.task.filter.completed.label;" value="completed" command="calendar_task_filter_command"/>
+                 <radio id="opt_open_filter" label="&calendar.task.filter.open.label;" value="open" command="calendar_task_filter_command"/>
                </radiogroup>
             </modevbox>
           </modevbox>
diff --git a/mozilla/calendar/locales/en-US/chrome/calendar/calendar.dtd b/mozilla/calendar/locales/en-US/chrome/calendar/calendar.dtd
index 91e519be97f..82ca680561a 100644
--- a/mozilla/calendar/locales/en-US/chrome/calendar/calendar.dtd
+++ b/mozilla/calendar/locales/en-US/chrome/calendar/calendar.dtd
@@ -196,6 +196,8 @@
 <!ENTITY calendar.task.filter.overdue.accesskey     "O">
 <!ENTITY calendar.task.filter.completed.label       "Completed Tasks">
 <!ENTITY calendar.task.filter.completed.accesskey   "C">
+<!ENTITY calendar.task.filter.open.label            "Incomplete Tasks">
+<!ENTITY calendar.task.filter.open.accesskey        "m">
 
 <!ENTITY calendar.task.details.title.label           "Title:">
 <!ENTITY calendar.task.details.organizer.label       "From:">