@@ -40,6 +40,7 @@ GSList *urgent_list;
 
 void task_dump_geometry(void *obj, int indent);
 int task_compute_desired_size(void *obj);
+void task_refresh_thumbnail(Task *task);
 
 char *task_get_tooltip(void *obj)
 {
@@ -50,6 +51,8 @@ 
 cairo_surface_t *task_get_thumbnail(void *obj)
 {
     Task *t = (Task *)obj;
+    if (!t->thumbnail)
+        task_refresh_thumbnail(t);
     return t->thumbnail;
 }
 
@@ -617,12 +620,22 @@ }
 
 void task_refresh_thumbnail(Task *task)
 {
+    if (task->current_state == TASK_ICONIFIED)
+        return;
+    double now = get_time();
+    if (now - task->thumbnail_last_update < 0.1)
+        return;
     cairo_surface_t *thumbnail = get_window_thumbnail(task->win);
     if (!thumbnail)
         return;
     if (task->thumbnail)
         cairo_surface_destroy(task->thumbnail);
     task->thumbnail = thumbnail;
+    task->thumbnail_last_update = get_time();
+    if (g_tooltip.mapped && (g_tooltip.area == &task->area)) {
+        tooltip_update_contents_for(&task->area);
+        tooltip_update();
+    }
 }
 
 void set_task_state(Task *task, TaskState state)
@@ -630,9 +643,8 @@ {
     if (!task || state == TASK_UNDEFINED || state >= TASK_STATE_COUNT)
         return;
 
-    if (state != TASK_ICONIFIED) {
-        task_refresh_thumbnail(task);
-    }
+    task_refresh_thumbnail(task);
+    taskbar_start_thumbnail_timer();
 
     if (state == TASK_ACTIVE && task->current_state != state) {
         clock_gettime(CLOCK_MONOTONIC, &task->last_activation_time);

@@ -75,6 +75,7 @@ double _text_posy;
     int _icon_x;
     int _icon_y;
     cairo_surface_t *thumbnail;
+    double thumbnail_last_update;
 } Task;
 
 extern timeout *urgent_timeout;
@@ -92,6 +93,7 @@ gboolean task_update_title(Task *task);
 void reset_active_task();
 void set_task_state(Task *task, TaskState state);
 void task_handle_mouse_event(Task *task, MouseAction action);
+void task_refresh_thumbnail(Task *task);
 
 // Given a pointer to the task that is currently under the mouse (current_task),
 // returns a pointer to the Task for the active window on the same taskbar.

@@ -46,6 +46,7 @@ gboolean hide_taskbar_if_empty;
 gboolean always_show_all_desktop_tasks;
 TaskbarSortMethod taskbar_sort_method;
 Alignment taskbar_alignment;
+static timeout *thumbnail_update_timer = NULL;
 
 static GList *taskbar_task_orderings = NULL;
 
@@ -54,6 +55,8 @@ int taskbar_compute_desired_size(void *obj);
 
 // Removes the task with &win = key. The other args are ignored.
 void taskbar_remove_task(Window *win);
+
+void taskbar_update_thumbnails(void *arg);
 
 guint win_hash(gconstpointer key)
 {
@@ -120,6 +123,7 @@ }
 
 void cleanup_taskbar()
 {
+    stop_timeout(thumbnail_update_timer);
     taskbar_save_orderings();
     if (win_to_task) {
         while (g_hash_table_size(win_to_task)) {
@@ -353,6 +357,12 @@ instantiate_area_gradients(&taskbar->area);
         }
     }
     init_taskbarname_panel(panel);
+    taskbar_start_thumbnail_timer();
+}
+
+void taskbar_start_thumbnail_timer()
+{
+    change_timeout(&thumbnail_update_timer, 100, 10 * 1000, taskbar_update_thumbnails, NULL);
 }
 
 void taskbar_init_fonts()
@@ -779,3 +789,17 @@ area->_on_change_layout(area);
         }
     }
 }
+
+void taskbar_update_thumbnails(void *arg)
+{
+    for (int i = 0; i < num_panels; i++) {
+        Panel *panel = &panels[i];
+        for (int j = 0; j < panel->num_desktops; j++) {
+            Taskbar *taskbar = &panel->taskbar[j];
+            for (GList *c = (taskbar->area.children && taskbarname_enabled) ? taskbar->area.children->next : taskbar->area.children; c; c = c->next) {
+                Task *t = (Task *)c->data;
+                task_refresh_thumbnail(t);
+            }
+        }
+    }
+}

@@ -72,6 +72,7 @@ void init_taskbar_panel(void *p);
 
 gboolean resize_taskbar(void *obj);
 void taskbar_default_font_changed();
+void taskbar_start_thumbnail_timer();
 
 // Reloads the entire list of tasks from the window manager and recreates the task buttons.
 void taskbar_refresh_tasklist();

@@ -54,6 +54,7 @@ 
 void cleanup_tooltip()
 {
     stop_tooltip_timeout();
+    stop_timeout(g_tooltip.update_timeout);
     tooltip_hide(NULL);
     tooltip_update_contents_for(NULL);
     if (g_tooltip.window)
@@ -333,6 +334,11 @@ {
     stop_timeout(g_tooltip.timeout);
 }
 
+void tooltip_update_contents_timeout(void *arg)
+{
+    tooltip_update_contents_for(g_tooltip.area);
+}
+
 void tooltip_update_contents_for(Area *area)
 {
     free_and_null(g_tooltip.tooltip_text);
@@ -345,6 +351,8 @@ if (area && area->_get_tooltip_image) {
         g_tooltip.image = area->_get_tooltip_image(area);
         if (g_tooltip.image)
             cairo_surface_reference(g_tooltip.image);
+        else
+            change_timeout(&g_tooltip.update_timeout, 300, 0, tooltip_update_contents_timeout, NULL);
     }
     g_tooltip.area = area;
 }

@@ -37,6 +37,7 @@ PangoFontDescription *font_desc;
     Color font_color;
     Background *bg;
     timeout *timeout;
+    timeout *update_timeout;
     cairo_surface_t *image;
 } Tooltip;