diff --git a/sample/tint2rc b/sample/tint2rc
index 0e153e8..03b0839 100644
--- a/sample/tint2rc
+++ b/sample/tint2rc
@@ -2,26 +2,38 @@
 # For information on manually configuring tint2 see http://code.google.com/p/tint2/wiki/Configure
 
 # Background definitions
-# ID 1
+# Background 1: panel
 rounded = 7
-border_width = 2
+border_width = 1
 background_color = #000000 60
 border_color = #FFFFFF 16
 
-# ID 2
+# Background 2: normal/iconified tasks
 rounded = 5
 border_width = 0
-background_color = #777777 40
-border_color = #FFFFFF 48
+background_color = #777777 20
+border_color = #777777 30
 
-# ID 3
+# Background 3: active tasks
 rounded = 5
 border_width = 1
-background_color = #777777 40
-border_color = #FFFFFF 60
+background_color = #777777 20
+border_color = #ffffff 40
+
+# Background 4: urgent tasks
+rounded = 5
+border_width = 1
+background_color = #aa4400 100
+border_color = #aa7733 100
+
+# Background 5: tooltips
+rounded = 2
+border_width = 1
+background_color = #ffffaa 100
+border_color = #999999 100
 
 # Panel
-panel_items = LTSC
+panel_items = LTSBC
 panel_monitor = all
 panel_position = bottom center horizontal
 panel_size = 95% 30
@@ -34,8 +46,8 @@ panel_background_id = 1
 
 # Panel Autohide
 autohide = 0
-autohide_show_timeout = 0.3
-autohide_hide_timeout = 2
+autohide_show_timeout = 0
+autohide_hide_timeout = 0.5
 autohide_height = 2
 strut_policy = follow_size
 
@@ -63,13 +75,13 @@ task_maximum_size = 140 35
 task_padding = 6 2
 task_background_id = 2
 task_active_background_id = 3
-task_urgent_background_id = 2
+task_urgent_background_id = 4
 task_iconified_background_id = 2
-task_tooltip = 0
+task_tooltip = 1
 urgent_nb_of_blink = 100000
 
 # Task Icons
-task_icon_asb = 80 0 0
+task_icon_asb = 100 0 0
 task_active_icon_asb = 100 0 0
 task_urgent_icon_asb = 100 0 0
 task_iconified_icon_asb = 70 0 0
@@ -86,8 +98,8 @@ font_shadow = 0
 mouse_left = toggle_iconify
 mouse_middle = none
 mouse_right = close
-mouse_scroll_up = toggle
-mouse_scroll_down = iconify
+mouse_scroll_up = prev_task
+mouse_scroll_down = next_task
 
 # System Tray
 systray_padding = 0 4 5
@@ -101,18 +113,18 @@ time1_format = %H:%M
 time1_font = sans 8
 time2_format = %A %d %B
 time2_font = sans 7
-clock_font_color = #FFFFFF 74
+clock_font_color = #FFFFFF 90
 clock_padding = 1 0
 clock_background_id = 0
 clock_rclick_command = orage
 
 # Tooltips
 tooltip_padding = 2 2
-tooltip_show_timeout = 0.7
-tooltip_hide_timeout = 0.3
-tooltip_background_id = 1
-tooltip_font = sans 10
-tooltip_font_color = #000000 80
+tooltip_show_timeout = 0.5
+tooltip_hide_timeout = 0.1
+tooltip_background_id = 5
+tooltip_font = sans 9
+tooltip_font_color = #222222 100
 
 # Battery
 battery_low_status = 10
@@ -120,7 +132,7 @@ battery_low_cmd = notify-send "battery low"
 battery_hide = 98
 bat1_font = sans 8
 bat2_font = sans 6
-battery_font_color = #FFFFFF 74
+battery_font_color = #FFFFFF 94
 battery_padding = 1 0
 battery_background_id = 0
 
diff --git a/src/battery/battery.c b/src/battery/battery.c
index bcac447..caf7630 100644
--- a/src/battery/battery.c
+++ b/src/battery/battery.c
@@ -274,9 +274,8 @@ void init_battery()
 	}
 #endif
 
-	if (battery_timeout == 0) {
-		battery_timeout = add_timeout(10, 10000, update_battery_tick, 0);
-	}
+	if (!battery_timeout)
+		battery_timeout = add_timeout(10, 10000, update_battery_tick, 0, &battery_timeout);
 }
 
 
diff --git a/src/clock/clock.c b/src/clock/clock.c
index 6938414..1592ea2 100644
--- a/src/clock/clock.c
+++ b/src/clock/clock.c
@@ -152,9 +152,9 @@ void init_clock()
 	if (!clock_timeout) {
 		if (time_format_needs_sec_ticks(time1_format) ||
 			time_format_needs_sec_ticks(time2_format)) {
-			clock_timeout = add_timeout(10, 1000, update_clocks_sec, 0);
+			clock_timeout = add_timeout(10, 1000, update_clocks_sec, 0, &clock_timeout);
 		} else {
-			clock_timeout = add_timeout(10, 1000, update_clocks_min, 0);
+			clock_timeout = add_timeout(10, 1000, update_clocks_min, 0, &clock_timeout);
 		}
 	}
 }
diff --git a/src/launcher/apps-common.c b/src/launcher/apps-common.c
index 6508e14..2d3ef5b 100644
--- a/src/launcher/apps-common.c
+++ b/src/launcher/apps-common.c
@@ -52,7 +52,7 @@ void expand_exec(DesktopEntry *entry, const char *path)
 	// %c -> Name
 	// %k -> path
 	if (entry->exec) {
-		char *exec2 = malloc(strlen(entry->exec) + (entry->name ? strlen(entry->name) : 1) + (entry->icon ? strlen(entry->icon) : 1) + 100);
+		char *exec2 = calloc(strlen(entry->exec) + (entry->name ? strlen(entry->name) : 1) + (entry->icon ? strlen(entry->icon) : 1) + 100, 1);
 		char *p, *q;
 		// p will never point to an escaped char
 		for (p = entry->exec, q = exec2; *p; p++, q++) {
diff --git a/src/launcher/icon-theme-common.c b/src/launcher/icon-theme-common.c
index f44eaee..17dc16c 100644
--- a/src/launcher/icon-theme-common.c
+++ b/src/launcher/icon-theme-common.c
@@ -561,8 +561,8 @@ char *get_icon_path_helper(GSList *themes, const char *icon_name, int size)
 					char *theme_name = ((IconTheme*)theme->data)->name;
 					char *dir_name = ((IconThemeDir*)dir->data)->name;
 					char *extension = (char*) ext->data;
-					char *file_name = malloc(strlen(base_name) + strlen(theme_name) +
-					strlen(dir_name) + strlen(icon_name) + strlen(extension) + 100);
+					char *file_name = calloc(strlen(base_name) + strlen(theme_name) +
+											 strlen(dir_name) + strlen(icon_name) + strlen(extension) + 100, 1);
 					// filename = directory/$(themename)/subdirectory/iconname.extension
 					sprintf(file_name, "%s/%s/%s/%s%s", base_name, theme_name, dir_name, icon_name, extension);
 					if (DEBUG_ICON_SEARCH)
@@ -620,8 +620,8 @@ char *get_icon_path_helper(GSList *themes, const char *icon_name, int size)
 			for (ext = extensions; ext; ext = g_slist_next(ext)) {
 				char *base_name = (char*) base->data;
 				char *extension = (char*) ext->data;
-				char *file_name = malloc(strlen(base_name) + strlen(icon_name) +
-					strlen(extension) + 100);
+				char *file_name = calloc(strlen(base_name) + strlen(icon_name) +
+										 strlen(extension) + 100, 1);
 				// filename = directory/iconname.extension
 				sprintf(file_name, "%s/%s%s", base_name, icon_name, extension);
 				if (DEBUG_ICON_SEARCH)
diff --git a/src/launcher/launcher.c b/src/launcher/launcher.c
index 796aa07..e91ed69 100644
--- a/src/launcher/launcher.c
+++ b/src/launcher/launcher.c
@@ -391,7 +391,7 @@ void free_icon(Imlib_Image icon)
 
 void launcher_action(LauncherIcon *icon, XEvent* evt)
 {
-	char *cmd = malloc(strlen(icon->cmd) + 10);
+	char *cmd = calloc(strlen(icon->cmd) + 10, 1);
 	sprintf(cmd, "(%s&)", icon->cmd);
 #if HAVE_SN
 	SnLauncherContext* ctx;
diff --git a/src/launcher/xsettings-client.c b/src/launcher/xsettings-client.c
index 23c0efa..00e83da 100644
--- a/src/launcher/xsettings-client.c
+++ b/src/launcher/xsettings-client.c
@@ -235,14 +235,14 @@ static XSettingsList *parse_settings (unsigned char *data, size_t len)
 			goto out;
 		}
 
-		setting = malloc (sizeof *setting);
+		setting = calloc (1, sizeof *setting);
 		if (!setting) {
 			result = XSETTINGS_NO_MEM;
 			goto out;
 		}
 		setting->type = XSETTINGS_TYPE_INT; /* No allocated memory */
 
-		setting->name = malloc (name_len + 1);
+		setting->name = calloc (name_len + 1, 1);
 		if (!setting->name) {
 			result = XSETTINGS_NO_MEM;
 			goto out;
@@ -276,7 +276,7 @@ static XSettingsList *parse_settings (unsigned char *data, size_t len)
 				goto out;
 			}
 
-			setting->data.v_string = malloc (v_int + 1);
+			setting->data.v_string = calloc (v_int + 1, 1);
 			if (!setting->data.v_string) {
 				result = XSETTINGS_NO_MEM;
 				goto out;
@@ -400,7 +400,7 @@ XSettingsClient *xsettings_client_new (Display *display, int screen, XSettingsNo
 {
 	XSettingsClient *client;
 
-	client = malloc (sizeof *client);
+	client = calloc (1, sizeof *client);
 	if (!client)
 		return NULL;
 
diff --git a/src/launcher/xsettings-common.c b/src/launcher/xsettings-common.c
index 9fe5011..c7637e4 100644
--- a/src/launcher/xsettings-common.c
+++ b/src/launcher/xsettings-common.c
@@ -34,12 +34,12 @@ xsettings_setting_copy (XSettingsSetting *setting)
 	XSettingsSetting *result;
 	size_t str_len;
 
-	result = malloc (sizeof *result);
+	result = calloc (1, sizeof *result);
 	if (!result)
 		return NULL;
 
 	str_len = strlen (setting->name);
-	result->name = malloc (str_len + 1);
+	result->name = calloc (str_len + 1, 1);
 	if (!result->name)
 		goto err;
 
@@ -57,7 +57,7 @@ xsettings_setting_copy (XSettingsSetting *setting)
 		break;
 	case XSETTINGS_TYPE_STRING:
 		str_len = strlen (setting->data.v_string);
-		result->data.v_string = malloc (str_len + 1);
+		result->data.v_string = calloc (str_len + 1, 1);
 		if (!result->data.v_string)
 			goto err;
 
@@ -90,7 +90,7 @@ xsettings_list_copy (XSettingsList *list)
 	{
 		XSettingsList *new_node;
 
-		new_node = malloc (sizeof *new_node);
+		new_node = calloc (1, sizeof *new_node);
 		if (!new_node)
 			goto error;
 
@@ -180,7 +180,7 @@ xsettings_list_insert (XSettingsList    **list,
 	XSettingsList *iter;
 	XSettingsList *last = NULL;
 
-	node = malloc (sizeof *node);
+	node = calloc (1, sizeof *node);
 	if (!node)
 		return XSETTINGS_NO_MEM;
 	node->setting = setting;
diff --git a/src/panel.c b/src/panel.c
index f104546..6b2e5e8 100644
--- a/src/panel.c
+++ b/src/panel.c
@@ -126,6 +126,7 @@ void cleanup_panel()
 		if (p->main_win)
 			XDestroyWindow(server.dsp, p->main_win);
 		p->main_win = 0;
+		stop_timeout(p->autohide_timeout);
 	}
 
 	free(panel_items_order);
@@ -167,7 +168,7 @@ void init_panel()
 	else
 		nb_panel = server.nb_monitor;
 
-	panel1 = malloc(nb_panel * sizeof(Panel));
+	panel1 = calloc(nb_panel, sizeof(Panel));
 	for (i=0 ; i < nb_panel ; i++) {
 		memcpy(&panel1[i], &panel_config, sizeof(Panel));
 	}
@@ -231,7 +232,7 @@ void init_panel()
 		}
 
 		if (panel_autohide)
-			add_timeout(panel_autohide_hide_timeout, 0, autohide_hide, p);
+			autohide_trigger_hide(p);
 		
 		visible_taskbar(p);
 	}
@@ -811,10 +812,7 @@ Area* click_area(Panel *panel, int x, int y)
 
 void stop_autohide_timeout(Panel* p)
 {
-	if (p->autohide_timeout) {
-		stop_timeout(p->autohide_timeout);
-		p->autohide_timeout = 0;
-	}
+	stop_timeout(p->autohide_timeout);
 }
 
 
@@ -875,10 +873,7 @@ void autohide_trigger_show(Panel* p)
 {
 	if (!p)
 		return;
-	if (p->autohide_timeout)
-		change_timeout(p->autohide_timeout, panel_autohide_show_timeout, 0, autohide_show, p);
-	else
-		p->autohide_timeout = add_timeout(panel_autohide_show_timeout, 0, autohide_show, p);
+	change_timeout(&p->autohide_timeout, panel_autohide_show_timeout, 0, autohide_show, p);
 }
 
 
@@ -893,8 +888,5 @@ void autohide_trigger_hide(Panel* p)
 	if (XQueryPointer(server.dsp, p->main_win, &root, &child, &xr, &yr, &xw, &yw, &mask))
 		if (child) return;  // mouse over one of the system tray icons
 
-	if (p->autohide_timeout)
-		change_timeout(p->autohide_timeout, panel_autohide_hide_timeout, 0, autohide_hide, p);
-	else
-		p->autohide_timeout = add_timeout(panel_autohide_hide_timeout, 0, autohide_hide, p);
+	change_timeout(&p->autohide_timeout, panel_autohide_hide_timeout, 0, autohide_hide, p);
 }
diff --git a/src/server.c b/src/server.c
index 0610ed4..44c570b 100644
--- a/src/server.c
+++ b/src/server.c
@@ -295,14 +295,14 @@ void get_monitors()
 			}
 
 			printf("xRandr: Found crtc's: %d\n", res->ncrtc );
-			server.monitor = malloc(res->ncrtc * sizeof(Monitor));
+			server.monitor = calloc(res->ncrtc, sizeof(Monitor));
 			for (i=0; i<res->ncrtc; ++i) {
 				XRRCrtcInfo* crtc_info = XRRGetCrtcInfo(server.dsp, res, res->crtcs[i]);
 				server.monitor[i].x = crtc_info->x;
 				server.monitor[i].y = crtc_info->y;
 				server.monitor[i].width = crtc_info->width;
 				server.monitor[i].height = crtc_info->height;
-				server.monitor[i].names = malloc((crtc_info->noutput+1) * sizeof(gchar*));
+				server.monitor[i].names = calloc((crtc_info->noutput+1), sizeof(gchar*));
 				for (j=0; j<crtc_info->noutput; ++j) {
 					XRROutputInfo* output_info = XRRGetOutputInfo(server.dsp, res, crtc_info->outputs[j]);
 					printf("xRandr: Linking output %s with crtc %d\n", output_info->name, i);
@@ -315,7 +315,7 @@ void get_monitors()
 			nbmonitor = res->ncrtc;
 		}
 		else if (info && nbmonitor > 0) {
-			server.monitor = malloc(nbmonitor * sizeof(Monitor));
+			server.monitor = calloc(nbmonitor, sizeof(Monitor));
 			for (i=0 ; i < nbmonitor ; i++) {
 				server.monitor[i].x = info[i].x_org;
 				server.monitor[i].y = info[i].y_org;
@@ -353,7 +353,7 @@ next:
 
 	if (!server.nb_monitor) {
 		server.nb_monitor = 1;
-		server.monitor = malloc(sizeof(Monitor));
+		server.monitor = calloc(1, sizeof(Monitor));
 		server.monitor[0].x = server.monitor[0].y = 0;
 		server.monitor[0].width = DisplayWidth (server.dsp, server.screen);
 		server.monitor[0].height = DisplayHeight (server.dsp, server.screen);
diff --git a/src/systray/systraybar.c b/src/systray/systraybar.c
index 15806b8..7034670 100644
--- a/src/systray/systraybar.c
+++ b/src/systray/systraybar.c
@@ -496,8 +496,7 @@ void remove_icon(TrayWindow *traywin)
 	XDestroyWindow(server.dsp, traywin->id);
 	XSync(server.dsp, False);
 	XSetErrorHandler(old);
-	if (traywin->render_timeout)
-		stop_timeout(traywin->render_timeout);
+	stop_timeout(traywin->render_timeout);
 	g_free(traywin);
 
 	// check empty systray
@@ -619,8 +618,8 @@ void systray_render_icon(TrayWindow* traywin)
 {
 	if (FORCE_COMPOSITED_RENDERING || server.real_transparency || systray.alpha != 100 || systray.brightness != 0 || systray.saturation != 0) {
 		// wine tray icons update whenever mouse is over them, so we limit the updates to 50 ms
-		if (traywin->render_timeout == 0)
-			traywin->render_timeout = add_timeout(50, 0, systray_render_icon_now, traywin);
+		if (!traywin->render_timeout)
+			traywin->render_timeout = add_timeout(50, 0, systray_render_icon_now, traywin, &traywin->render_timeout);
 	}
 	else {
 		//			Pixmap pix = XCreatePixmap(server.dsp, server.root_win, traywin->width, traywin->height, server.depth);
diff --git a/src/taskbar/task.c b/src/taskbar/task.c
index 60c0632..62303b2 100644
--- a/src/taskbar/task.c
+++ b/src/taskbar/task.c
@@ -87,7 +87,7 @@ Task *add_task (Window win)
 		if (new_tsk.desktop != ALLDESKTOP && new_tsk.desktop != j) continue;
 
 		tskbar = &panel1[monitor].taskbar[j];
-		new_tsk2 = malloc(sizeof(Task));
+		new_tsk2 = calloc(1, sizeof(Task));
 		memcpy(&new_tsk2->area, &panel1[monitor].g_task.area, sizeof(Area));
 		new_tsk2->area.parent = tskbar;
 		new_tsk2->win = new_tsk.win;
@@ -115,7 +115,7 @@ Task *add_task (Window win)
 		g_ptr_array_add(task_group, new_tsk2);
 		//printf("add_task panel %d, desktop %d, task %s\n", i, j, new_tsk2->title);
 	}
-	Window* key = malloc(sizeof(Window));
+	Window* key = calloc(1, sizeof(Window));
 	*key = new_tsk.win;
 	g_hash_table_insert(win_to_task_table, key, task_group);
 	set_task_state(new_tsk2, new_tsk.current_state);
@@ -195,14 +195,14 @@ int get_title(Task *tsk)
 		if (!name || !strlen(name)) {
 			name = server_get_property (tsk->win, server.atom.WM_NAME, XA_STRING, 0);
 			if (!name || !strlen(name)) {
-				name = malloc(10);
+				name = calloc(10, 1);
 				strcpy(name, "Untitled");
 			}
 		}
 	}
 
 	// add space before title
-	title = malloc(strlen(name)+2);
+	title = calloc(strlen(name)+2, 1);
 	if (panel->g_task.icon) strcpy(title, " ");
 	else title[0] = 0;
 	strcat(title, name);
@@ -620,7 +620,7 @@ void add_urgent(Task *tsk)
 	urgent_list = g_slist_prepend(urgent_list, tsk);
 
 	if (!urgent_timeout)
-		urgent_timeout = add_timeout(10, 1000, blink_urgent, 0);
+		urgent_timeout = add_timeout(10, 1000, blink_urgent, 0, &urgent_timeout);
 
 	Panel *panel = tsk->area.panel;
 	if (panel->is_hidden)
diff --git a/src/taskbar/taskbar.c b/src/taskbar/taskbar.c
index 33aa864..5b0f510 100644
--- a/src/taskbar/taskbar.c
+++ b/src/taskbar/taskbar.c
@@ -109,7 +109,6 @@ void cleanup_taskbar()
 	urgent_list = NULL;
 
 	stop_timeout(urgent_timeout);
-	urgent_timeout = NULL;
 }
 
 
diff --git a/src/tint.c b/src/tint.c
index 3593258..607692f 100644
--- a/src/tint.c
+++ b/src/tint.c
@@ -1350,7 +1350,7 @@ start:
 								cmd_length += 2; // &)
 								cmd_length += 1; // terminator
 
-								char *cmd = malloc(cmd_length);
+								char *cmd = calloc(cmd_length, 1);
 								cmd[0] = '\0';
 								strcat(cmd, "(");
 								strcat(cmd, dnd_launcher_exec);
diff --git a/src/tooltip/tooltip.c b/src/tooltip/tooltip.c
index 66bc29b..294c837 100644
--- a/src/tooltip/tooltip.c
+++ b/src/tooltip/tooltip.c
@@ -86,7 +86,7 @@ void init_tooltip()
 void tooltip_trigger_show(Area* area, Panel* p, XEvent *e)
 {
 	// Position the tooltip in the center of the area
-	x = area->posx + area->width / 2 + e->xmotion.x_root - e->xmotion.x;
+	x = area->posx + MIN(area->width / 3, 22) + e->xmotion.x_root - e->xmotion.x;
 	y = area->posy + area->height / 2 + e->xmotion.y_root - e->xmotion.y;
 	just_shown = 1;
 	g_tooltip.panel = p;
@@ -108,7 +108,6 @@ void tooltip_show(void* arg)
 	XTranslateCoordinates( server.dsp, server.root_win, g_tooltip.panel->main_win, x, y, &mx, &my, &w);
 	Area* area;
 	area = click_area(g_tooltip.panel, mx, my);
-	stop_tooltip_timeout();
 	if (!g_tooltip.mapped && area->_get_tooltip_text) {
 		tooltip_copy_text(area);
 		g_tooltip.mapped = True;
@@ -275,7 +274,6 @@ void tooltip_trigger_hide(Tooltip* tooltip)
 
 void tooltip_hide(void* arg)
 {
-	stop_tooltip_timeout();
 	if (g_tooltip.mapped) {
 		g_tooltip.mapped = False;
 		XUnmapWindow(server.dsp, g_tooltip.window);
@@ -286,26 +284,19 @@ void tooltip_hide(void* arg)
 
 void start_show_timeout()
 {
-	if (g_tooltip.timeout)
-		change_timeout(g_tooltip.timeout, g_tooltip.show_timeout_msec, 0, tooltip_show, 0);
-	else
-		g_tooltip.timeout = add_timeout(g_tooltip.show_timeout_msec, 0, tooltip_show, 0);
+	change_timeout(&g_tooltip.timeout, g_tooltip.show_timeout_msec, 0, tooltip_show, 0);
 }
 
 
 void start_hide_timeout()
 {
-	if (g_tooltip.timeout)
-		change_timeout(g_tooltip.timeout, g_tooltip.hide_timeout_msec, 0, tooltip_hide, 0);
-	else
-		g_tooltip.timeout = add_timeout(g_tooltip.hide_timeout_msec, 0, tooltip_hide, 0);
+	change_timeout(&g_tooltip.timeout, g_tooltip.hide_timeout_msec, 0, tooltip_hide, 0);
 }
 
 
 void stop_tooltip_timeout()
 {
 	stop_timeout(g_tooltip.timeout);
-	g_tooltip.timeout = NULL;
 }
 
 
diff --git a/src/util/timer.c b/src/util/timer.c
index 8b0cb5d..65f5b85 100644
--- a/src/util/timer.c
+++ b/src/util/timer.c
@@ -44,6 +44,7 @@ struct _timeout {
 	void (*_callback)(void*);
 	void* arg;
 	multi_timeout* multi_timeout;
+	timeout **self;
 };
 
 void add_timeout_intern(int value_msec, int interval_msec, void(*_callback)(void*), void* arg, timeout* t);
@@ -74,6 +75,8 @@ void cleanup_timeout()
 		timeout* t = timeout_list->data;
 		if (t->multi_timeout)
 			stop_multi_timeout(t);
+		if (t->self)
+			*t->self = NULL;
 		free(t);
 		timeout_list = g_slist_remove(timeout_list, t);
 	}
@@ -95,25 +98,26 @@ void cleanup_timeout()
 	* however it's save to call it.
 **/
 
-timeout* add_timeout(int value_msec, int interval_msec, void (*_callback)(void*), void* arg)
+timeout* add_timeout(int value_msec, int interval_msec, void (*_callback)(void*), void* arg, timeout **self)
 {
-	timeout* t = malloc(sizeof(timeout));
-	t->multi_timeout = 0;
+	timeout* t = calloc(1, sizeof(timeout));
+	t->self = self;
 	add_timeout_intern(value_msec, interval_msec, _callback, arg, t);
 	return t;
 }
 
 
-void change_timeout(timeout *t, int value_msec, int interval_msec, void(*_callback)(), void* arg)
+void change_timeout(timeout **t, int value_msec, int interval_msec, void(*_callback)(), void* arg)
 {
-	if ( g_slist_find(timeout_list, t) == 0 && g_hash_table_lookup(multi_timeouts, t) == 0)
-		printf("programming error: timeout already deleted...");
+	if (!((timeout_list && g_slist_find(timeout_list, *t)) ||
+		  (multi_timeouts && g_hash_table_lookup(multi_timeouts, *t))))
+		*t = add_timeout(value_msec, interval_msec, _callback, arg, t);
 	else {
-		if (t->multi_timeout)
-			remove_from_multi_timeout((timeout*)t);
+		if ((*t)->multi_timeout)
+			remove_from_multi_timeout(*t);
 		else
-			timeout_list = g_slist_remove(timeout_list, t);
-		add_timeout_intern(value_msec, interval_msec, _callback, arg, (timeout*)t);
+			timeout_list = g_slist_remove(timeout_list, *t);
+		add_timeout_intern(value_msec, interval_msec, _callback, arg, *t);
 	}
 }
 
@@ -149,31 +153,40 @@ void callback_timeout_expired()
 		if (compare_timespecs(&t->timeout_expires, &cur_time) <= 0) {
 			// it's time for the callback function
 			t->_callback(t->arg);
+			// If _callback() calls stop_timeout(t) the timer 't' was freed and is not in the timeout_list
 			if (g_slist_find(timeout_list, t)) {
-				// if _callback() calls stop_timeout(t) the timeout 't' was freed and is not in the timeout_list
+				// Timer still exists
 				timeout_list = g_slist_remove(timeout_list, t);
-				if (t->interval_msec > 0)
+				if (t->interval_msec > 0) {
 					add_timeout_intern(t->interval_msec, t->interval_msec, t->_callback, t->arg, t);
-				else
+				} else {
+					// Destroy single-shot timer
+					if (t->self)
+						*t->self = NULL;
 					free(t);
+				}
 			}
-		}
-		else
+		} else {
 			return;
+		}
 	}
 }
 
 
 void stop_timeout(timeout* t)
 {
-	if (!multi_timeouts || !t)
+	if (!t)
 		return;
 	// if not in the list, it was deleted in callback_timeout_expired
-	if (g_slist_find(timeout_list, t) || g_hash_table_lookup(multi_timeouts, t)) {
-		if (t->multi_timeout)
-			remove_from_multi_timeout((timeout*)t);
-		timeout_list = g_slist_remove(timeout_list, t);
-		free((void*)t);
+	if ((timeout_list && g_slist_find(timeout_list, t)) ||
+		(multi_timeouts && g_hash_table_lookup(multi_timeouts, t))) {
+		if (multi_timeouts && t->multi_timeout)
+			remove_from_multi_timeout(t);
+		if (timeout_list)
+			timeout_list = g_slist_remove(timeout_list, t);
+		if (t->self)
+			*t->self = NULL;
+		free(t);
 	}
 }
 
@@ -198,7 +211,7 @@ void add_timeout_intern(int value_msec, int interval_msec, void(*_callback)(), v
 gint compare_timeouts(gconstpointer t1, gconstpointer t2)
 {
 	return compare_timespecs(&((timeout*)t1)->timeout_expires,
-													 &((timeout*)t2)->timeout_expires);
+							 &((timeout*)t2)->timeout_expires);
 }
 
 
@@ -262,12 +275,13 @@ int align_with_existing_timeouts(timeout *t)
 			if (t->interval_msec % t2->interval_msec == 0 || t2->interval_msec % t->interval_msec == 0) {
 				if (multi_timeouts == 0)
 					multi_timeouts = g_hash_table_new(0, 0);
-				if (!t->multi_timeout && !t2->multi_timeout)
+				if (!t->multi_timeout && !t2->multi_timeout) {
 					// both timeouts can be aligned, but there is no multi timeout for them
 					create_multi_timeout(t, t2);
-				else
+				} else {
 					// there is already a multi timeout, so we append the new timeout to the multi timeout
 					append_multi_timeout(t, t2);
+				}
 				return 1;
 			}
 		}
@@ -295,10 +309,10 @@ int calc_multi_timeout_interval(multi_timeout_handler* mth)
 
 void create_multi_timeout(timeout* t1, timeout* t2)
 {
-	multi_timeout* mt1 = malloc(sizeof(multi_timeout));
-	multi_timeout* mt2 = malloc(sizeof(multi_timeout));
-	multi_timeout_handler* mth = malloc(sizeof(multi_timeout_handler));
-	timeout* real_timeout = malloc(sizeof(timeout));
+	multi_timeout* mt1 = calloc(1, sizeof(multi_timeout));
+	multi_timeout* mt2 = calloc(1, sizeof(multi_timeout));
+	multi_timeout_handler* mth = calloc(1, sizeof(multi_timeout_handler));
+	timeout* real_timeout = calloc(1, sizeof(timeout));
 
 	mth->timeout_list = 0;
 	mth->timeout_list = g_slist_prepend(mth->timeout_list, t1);
@@ -331,7 +345,7 @@ void append_multi_timeout(timeout* t1, timeout* t2)
 		t1 = tmp;
 	}
 
-	multi_timeout* mt = malloc(sizeof(multi_timeout));
+	multi_timeout* mt = calloc(1, sizeof(multi_timeout));
 	multi_timeout_handler* mth = g_hash_table_lookup(multi_timeouts, t1);
 
 	mth->timeout_list = g_slist_prepend(mth->timeout_list, t2);
diff --git a/src/util/timer.h b/src/util/timer.h
index 250e7e0..6411b2f 100644
--- a/src/util/timer.h
+++ b/src/util/timer.h
@@ -21,7 +21,6 @@
 
 #include <glib.h>
 
-extern GSList* timeout_list;
 extern struct timeval next_timeout;
 
 
@@ -30,26 +29,33 @@ typedef struct _timeout timeout;
 
 // timer functions
 /**
-  * Single shot timer (i.e. timer with interval_msec == 0) are deleted automatically as soon as they expire
+  * Single shot timers (i.e. timers with interval_msec == 0) are deleted automatically as soon as they expire,
   * i.e. you do not need to stop them, however it is safe to call stop_timeout for these timers.
+  * You can pass the address of the variable storing the pointer to the timer as 'self' in add_timeout, in which
+  * case it is used to clear the pointer if the timer is destroyed automatically. This enforces the timeout pointers
+  * to be either valid or NULL.
   * Periodic timeouts are aligned to each other whenever possible, i.e. one interval_msec is an
   * integral multiple of the other.
 **/
 
-/** default global data **/
+/** Initializes default global data. **/
 void default_timeout();
 
-/** freed memory : stops all timeouts **/
+/** Cleans up: stops all timers and frees memory. **/
 void cleanup_timeout();
 
-/** installs a timeout with the first timeout of 'value_msec' and then a periodic timeout with
-  * 'interval_msec'. '_callback' is the callback function when the timer reaches the timeout.
-  * returns a pointer to the timeout, which is needed for stopping it again
+/** Installs a timer with the first timeout after 'value_msec' and then an optional periodic timeout every
+  * 'interval_msec' (set it to 0 to prevent periodic timeouts).
+  * '_callback' is the function called when the timer reaches the timeout.
+  * 'arg' is the argument passed to the callback function.
+  * 'self' is an optional pointer to a timeout* variable. If non-NULL, the variable is set to NULL when the timer
+  * is destroyed (with stop_timeout, cleanup_timeout or when the timer expires and it is single-shot).
+  * Returns a pointer to the timer, which is needed for stopping/changing it.
 **/
-timeout* add_timeout(int value_msec, int interval_msec, void (*_callback)(void*), void* arg);
+timeout* add_timeout(int value_msec, int interval_msec, void (*_callback)(void*), void* arg, timeout **self);
 
-/** changes timeout 't'. If timeout 't' does not exist, nothing happens **/
-void change_timeout(timeout* t, int value_msec, int interval_msec, void (*_callback)(void*), void* arg);
+/** Changes timer 't'. If it does not exist, a new timer is created, with self set to 't'. **/
+void change_timeout(timeout** t, int value_msec, int interval_msec, void (*_callback)(void*), void* arg);
 
 /** stops the timeout 't' **/
 void stop_timeout(timeout* t);