Index: orage/src/mainbox.c
===================================================================
--- orage/src/mainbox.c	(revision 247)
+++ orage/src/mainbox.c	(revision 254)
@@ -357,19 +357,43 @@
             , G_CALLBACK(mHelp_about_activate_cb),(gpointer) cal);
 }
 
+/*
+    Remove the reference to a destroyed appointment window from
+    its todo label.
+*/
+static void appt_window_destroyed(GtkWidget *widget
+        , gpointer user_data)
+{
+    GtkWidget *wd = (GtkWidget*)user_data;
+    g_object_set_data(G_OBJECT(wd), "APPT_WINDOW", NULL);
+}
+
 static void todo_clicked(GtkWidget *widget
         , GdkEventButton *event, gpointer *user_data)
 {
 #undef P_N
 #define P_N "todo_clicked: "
     gchar *uid;
+    GtkWidget *win;
 
 #ifdef ORAGE_DEBUG
     orage_message(-100, P_N);
 #endif
     if (event->type==GDK_2BUTTON_PRESS) {
         uid = g_object_get_data(G_OBJECT(widget), "UID");
-        create_appt_win("UPDATE", uid);
+        win=(GtkWidget*)g_object_get_data(G_OBJECT(widget), "APPT_WINDOW");
+
+        if (win) {
+            /* window already exists, just bring it to the front and give it focus. */
+            gtk_window_present(GTK_WINDOW(win));
+        }
+        else {
+            /* create a new window. */
+            win=create_appt_win("UPDATE", uid)->Window;
+            g_signal_connect((gpointer) win, "destroy"
+                , G_CALLBACK(appt_window_destroyed), widget);
+            g_object_set_data(G_OBJECT(widget), "APPT_WINDOW", win);
+        }
     }
 }