[gnome-applets/wip-geiger-monitor] window-picker: add weak reference for monitor

[Sebastian Geiger <segeiger src gnome org>]

commit 154ac3b354f781e07479f8af7a9cbeb4dd053f29
Author: Sebastian Geiger <sbastig gmx net>
Date:   Sat Mar 28 17:18:56 2020 +0100

    window-picker: add weak reference for monitor

 gnome-applets/window-picker/task-item.c | 20 ++++++++++++++++++--
 1 file changed, 18 insertions(+), 2 deletions(-)
---
diff --git a/gnome-applets/window-picker/task-item.c b/gnome-applets/window-picker/task-item.c
index b52b72aee..e55276935 100644
--- a/gnome-applets/window-picker/task-item.c
+++ b/gnome-applets/window-picker/task-item.c
@@ -580,6 +580,20 @@ get_window_monitor (WnckWindow *window)
     return window_monitor;
 }
 
+static void
+set_monitor (TaskItem *item, GdkMonitor *monitor)
+{
+    if (item->monitor)
+        g_object_remove_weak_pointer (G_OBJECT (item->monitor),
+                                      (gpointer *) &item->monitor);
+
+    item->monitor = monitor;
+
+    if (item->monitor)
+        g_object_add_weak_pointer (G_OBJECT (item->monitor),
+                                   (gpointer *) &item->monitor);
+}
+
 static void
 on_window_geometry_changed (WnckWindow *window,
                             TaskItem   *item)
@@ -590,9 +604,10 @@ on_window_geometry_changed (WnckWindow *window,
     window_monitor = get_window_monitor (window);
 
     old_monitor = item->monitor;
+
     if (old_monitor != window_monitor)
       {
-        item->monitor = window_monitor;
+        set_monitor (item, window_monitor);
 
         g_signal_emit (item, task_item_signals[TASK_ITEM_MONITOR_CHANGED], 0);
       }
@@ -1027,7 +1042,8 @@ GtkWidget *task_item_new (WpApplet* windowPickerApplet, WnckWindow *window) {
     screen = wnck_window_get_screen (window);
     taskItem->screen = screen;
     taskItem->windowPickerApplet = windowPickerApplet;
-    taskItem->monitor = get_window_monitor (window);
+
+    set_monitor (taskItem, get_window_monitor (window));
 
     g_signal_connect_object (windowPickerApplet,
                              "placement-changed",