diff --git a/lib/solaar/appinstance.py b/lib/solaar/appinstance.py
index 74601aa6..5e149914 100644
--- a/lib/solaar/appinstance.py
+++ b/lib/solaar/appinstance.py
@@ -12,16 +12,22 @@ import fcntl as _fcntl
 import os.path as _path
 import os as _os
 
+from logging import getLogger, DEBUG as _DEBUG
+_log = getLogger('solaar.appinstance')
+del getLogger
+
 
 def check():
 	# ensure no more than a single instance runs at a time
 	lock_fd = None
 	for p in _os.environ.get('XDG_RUNTIME_DIR'), '/run/lock', '/var/lock', _os.environ.get('TMPDIR', '/tmp'):
+		# pick the first temporary writable folder
 		if p and _path.isdir(p) and _os.access(p, _os.W_OK):
 			lock_path = _path.join(p, 'solaar.single-instance.%d' % _os.getuid())
 			try:
 				lock_fd = open(lock_path, 'wb')
-				# print ("Single instance lock file is %s" % lock_path)
+				if _log.isEnabledFor(_DEBUG):
+					_log.debug("single-instance lock file is %s", lock_path)
 				break
 			except:
 				pass
@@ -29,9 +35,12 @@ def check():
 	if lock_fd:
 		try:
 			_fcntl.flock(lock_fd, _fcntl.LOCK_EX | _fcntl.LOCK_NB)
+			if _log.isEnabledFor(_DEBUG):
+				_log.debug("acquired single-instance lock (%s)", lock_fd)
 			return lock_fd
 		except IOError as e:
 			if e.errno == 11:
+				_log.warn("lock file is busy, solaar already running: %s", e)
 				import sys
 				sys.exit("solaar: error: Solaar is already running.")
 			else:
@@ -42,6 +51,8 @@ def check():
 
 
 def close(lock_fd):
+	if _log.isEnabledFor(_DEBUG):
+		_log.debug("releasing single-instance lock (%s)", lock_fd)
 	if lock_fd:
 		_fcntl.flock(lock_fd, _fcntl.LOCK_UN)
 		lock_fd.close()
diff --git a/lib/solaar/gtk.py b/lib/solaar/gtk.py
index 7cc89cf4..ec86358c 100644
--- a/lib/solaar/gtk.py
+++ b/lib/solaar/gtk.py
@@ -40,6 +40,10 @@ def _parse_arguments():
 
 
 def _run(args):
+	from logging import getLogger
+	_log = getLogger('solaar.gtk')
+	del getLogger
+
 	import solaar.ui as ui
 
 	ui.notify.init()
@@ -54,6 +58,8 @@ def _run(args):
 		assert action is not None
 		assert device_info is not None
 
+		_log.info("receiver event %s: %s", action, device_info)
+
 		# whatever the action, stop any previous receivers at this path
 		l = listeners.pop(device_info.path, None)
 		if l is not None:
@@ -94,10 +100,10 @@ def _run(args):
 
 		GLib.idle_add(ui.status_icon.update, status_icon, device)
 		if alert & ALERT.ATTENTION:
-			GLib.idle_add(ui.status_icon.attention, status_icon)
+			GLib.idle_add(ui.status_icon.attention, status_icon, reason)
 
-		popup_window = alert & (ALERT.SHOW_WINDOW | ALERT.ATTENTION)
-		GLib.idle_add(ui.main_window.update, device, popup_window, status_icon)
+		need_popup = alert & (ALERT.SHOW_WINDOW | ALERT.ATTENTION)
+		GLib.idle_add(ui.main_window.update, device, need_popup, status_icon)
 
 		if alert & ALERT.NOTIFICATION:
 			GLib.idle_add(ui.notify.show, device, reason)
@@ -105,15 +111,21 @@ def _run(args):
 	# ugly...
 	def _startup_check_receiver():
 		if not listeners:
+			# this is called on the Main (GTK) thread, so we can make direct calls
 			ui.notify.alert('No receiver found.')
 			ui.status_icon.update(status_icon)
+			ui.status_icon.attention(status_icon, 'No receiver found.')
+	# check for a receiver 1 second after the app was started
 	GLib.timeout_add(1000, _startup_check_receiver)
 
 	from logitech.unifying_receiver import base as _base
+	# receiver add/remove events will start/stop listener threads
 	GLib.timeout_add(10, _base.notify_on_receivers, handle_receivers_events)
 	from gi.repository import Gtk
 	Gtk.main()
-	# ui.status_icon.destroy(status_icon)
+	# this is unnecessary for the Gtk.StatusIcon implementation
+	# but the AppIdicator implementation may need it to make the indicator go away
+	ui.status_icon.destroy(status_icon)
 
 	for l in listeners.values():
 		l.stop()
diff --git a/lib/solaar/ui/main_window.py b/lib/solaar/ui/main_window.py
index facd1f4a..9cc2503d 100644
--- a/lib/solaar/ui/main_window.py
+++ b/lib/solaar/ui/main_window.py
@@ -471,7 +471,7 @@ def _update_device_box(frame, dev):
 	_config_panel.update(frame)
 
 
-def update(device, popup=False, status_icon=None):
+def update(device, need_popup=False, status_icon=None):
 	assert device is not None
 	# print ("main_window.update", device)
 
@@ -483,7 +483,7 @@ def update(device, popup=False, status_icon=None):
 
 	if w:
 		if receiver:
-			if popup:
+			if need_popup:
 				_show(w, status_icon)
 			vbox = w.get_child()
 			frames = list(vbox.get_children())
diff --git a/lib/solaar/ui/status_icon.py b/lib/solaar/ui/status_icon.py
index 2033c562..f2126cd3 100644
--- a/lib/solaar/ui/status_icon.py
+++ b/lib/solaar/ui/status_icon.py
@@ -8,18 +8,27 @@ from logging import getLogger, DEBUG as _DEBUG
 _log = getLogger('solaar.ui.tray')
 del getLogger
 
+from time import time as _timestamp
+
 from gi.repository import Gtk, GLib
+from gi.repository.Gdk import ScrollDirection
 
 from solaar import NAME
 from . import action as _action, icons as _icons
 from logitech.unifying_receiver import status as _status
 
+_TRAY_ICON_SIZE = 32 #  pixels
 _MENU_ICON_SIZE = Gtk.IconSize.LARGE_TOOLBAR
 
 #
 #
 #
 
+# for which device to show the battery info in systray, if more than one
+_picked_device = None
+
+
+
 def _create_common(icon, menu_activate_callback):
 	icon._devices_info = []
 
@@ -28,12 +37,13 @@ def _create_common(icon, menu_activate_callback):
 	icon._menu_activate_callback = menu_activate_callback
 	icon._menu = menu = Gtk.Menu()
 
+	# per-device menu entries will be generated as-needed
+
 	no_receiver = Gtk.MenuItem.new_with_label('No receiver found')
 	no_receiver.set_sensitive(False)
 	menu.append(no_receiver)
-
-	# per-device menu entries will be generated as-needed
 	menu.append(Gtk.SeparatorMenuItem.new())
+
 	menu.append(_action.about.create_menu_item())
 	menu.append(_action.make('application-exit', 'Quit', Gtk.main_quit).create_menu_item())
 	menu.show_all()
@@ -42,55 +52,139 @@ def _create_common(icon, menu_activate_callback):
 try:
 	from gi.repository import AppIndicator3
 
-	_log.debug("using AppIndicator3")
+	_log.info("using AppIndicator3")
+
+
+	_last_scroll = 0
+	def _scroll(ind, _, direction):
+		if direction != ScrollDirection.UP and direction != ScrollDirection.DOWN:
+			# ignore all other directions
+			return
+
+		if len(ind._devices_info) < 4:
+			# don't bother with scrolling when there's only one receiver
+			# with only one device (3 = [receiver, device, separator])
+			return
+
+		# scroll events come way too fast (at least 5-6 at once)
+		# so take a little break between them
+		global _last_scroll
+		now = _timestamp()
+		if now - _last_scroll < 0.33:  # seconds
+			return
+		_last_scroll = now
+
+		# if _log.isEnabledFor(_DEBUG):
+		# 	_log.debug("scroll direction %s", direction)
+
+		global _picked_device
+		candidate = None
+
+		if _picked_device is None:
+			for info in ind._devices_info:
+				# pick first peripheral found
+				if info[1] is not None:
+					candidate = info
+					break
+		else:
+			found = False
+			for info in ind._devices_info:
+				if not info[1]:
+					# only conside peripherals
+					continue
+				# compare peripheral serials
+				if info[1] == _picked_device[1]:
+					if direction == ScrollDirection.UP and candidate:
+						# select previous device
+						break
+					found = True
+				else:
+					if found:
+						candidate = info
+						if direction == ScrollDirection.DOWN:
+							break
+						# if direction is up, but no candidate found before _picked,
+						# let it run through all candidates, will get stuck with the last one
+					else:
+						if direction == ScrollDirection.DOWN:
+							# only use the first one, in case no candidates are after _picked
+							if candidate is None:
+								candidate = info
+						else:
+							candidate = info
+
+			# if the last _picked_device is gone, clear it
+			# the candidate will be either the first or last one remaining,
+			# depending on the scroll direction
+			if not found:
+				_picked_device = None
+
+		_picked_device = candidate or _picked_device
+		if _log.isEnabledFor(_DEBUG):
+			_log.debug("scroll: picked %s", _picked_device)
+		_update_tray_icon(ind)
 
-	# def _scroll(ind, delta, direction):
-	# 	if _log.isEnabledFor(_DEBUG):
-	# 		_log.debug("scroll delta %s direction %s", delta, direction)
 
 	def create(activate_callback, menu_activate_callback):
 		assert activate_callback
 		assert menu_activate_callback
 
-		ind = AppIndicator3.Indicator.new(
+		theme_paths = Gtk.IconTheme.get_default().get_search_path()
+
+		ind = AppIndicator3.Indicator.new_with_path(
 						'indicator-solaar',
 						_icons.TRAY_INIT,
-						AppIndicator3.IndicatorCategory.HARDWARE)
+						AppIndicator3.IndicatorCategory.HARDWARE,
+						':'.join(theme_paths))
 		ind.set_status(AppIndicator3.IndicatorStatus.ACTIVE)
-		ind.set_label(NAME, NAME)
-
-		# theme_paths = Gtk.IconTheme.get_default().get_search_path()
-		# ind.set_icon_theme_path(':'.join(theme_paths))
-
-		# ind.set_icon(_icons.TRAY_INIT)
-		ind.set_attention_icon(_icons.TRAY_ATTENTION)
+		ind.set_attention_icon_full(_icons.TRAY_ATTENTION, '')
+		# ind.set_label(NAME, NAME)
 
 		_create_common(ind, menu_activate_callback)
 		ind.set_menu(ind._menu)
 
-		# ind.connect('scroll-event', _scroll)
+		ind.connect('scroll-event', _scroll)
 
 		return ind
 
 
-	# def destroy(ind):
-	# 	ind.set_status(AppIndicator3.IndicatorStatus.PASSIVE)
+	def destroy(ind):
+		ind.set_status(AppIndicator3.IndicatorStatus.PASSIVE)
 
 
-	def _update_icon(ind, icon_name, tooltip):
-		icon_file = _icons.icon_file(icon_name, 32)
-		ind.set_icon(icon_file)
-		# ind.set_icon_full(icon_name, tooltip)
+	def _update_tray_icon(ind):
+		if _picked_device:
+			_, _, name, _, device_status = _picked_device
+			battery_level = device_status.get(_status.BATTERY_LEVEL)
+			battery_charging = device_status.get(_status.BATTERY_CHARGING)
+			tray_icon_name = _icons.battery(battery_level, battery_charging)
+
+			description =  '%s: %s' % (name, device_status)
+		else:
+			# there may be a receiver, but no peripherals
+			tray_icon_name = _icons.TRAY_OKAY if ind._devices_info else _icons.TRAY_INIT
+			description = '%s: no receivers found' % NAME
+
+		# icon_file = _icons.icon_file(icon_name, _TRAY_ICON_SIZE)
+		ind.set_icon_full(tray_icon_name, description)
 
 
-	def attention(ind):
+	def _update_menu_icon(image_widget, icon_name):
+		image_widget.set_from_icon_name(icon_name, _MENU_ICON_SIZE)
+		# icon_file = _icons.icon_file(icon_name, _MENU_ICON_SIZE)
+		# image_widget.set_from_file(icon_file)
+		# image_widget.set_pixel_size(_TRAY_ICON_SIZE)
+
+
+	def attention(ind, reason=None):
 		if ind.get_status != AppIndicator3.IndicatorStatus.ATTENTION:
+			ind.set_attention_icon_full(_icons.TRAY_ATTENTION, reason or '')
 			ind.set_status(AppIndicator3.IndicatorStatus.ATTENTION)
 			GLib.timeout_add(10 * 1000, ind.set_status, AppIndicator3.IndicatorStatus.ACTIVE)
 
 except ImportError:
 
-	_log.debug("using StatusIcon")
+	_log.info("using StatusIcon")
 
 	def create(activate_callback, menu_activate_callback):
 		assert activate_callback
@@ -110,31 +204,46 @@ except ImportError:
 		return icon
 
 
-	# def destroy(icon):
-	# 	icon.set_visible(False)
+	def destroy(icon):
+		icon.set_visible(False)
 
 
-	def _update_icon(icon, icon_name, tooltip):
-		icon.set_from_icon_name(icon_name)
+	def _update_tray_icon(icon):
+		tooltip_lines = _generate_tooltip_lines(icon._devices_info)
+		tooltip = '\n'.join(tooltip_lines).rstrip('\n')
 		icon.set_tooltip_markup(tooltip)
 
+		if _picked_device:
+			_, _, name, _, device_status = _picked_device
+			battery_level = device_status.get(_status.BATTERY_LEVEL)
+			battery_charging = device_status.get(_status.BATTERY_CHARGING)
+			tray_icon_name = _icons.battery(battery_level, battery_charging)
+		else:
+			# there may be a receiver, but no peripherals
+			tray_icon_name = _icons.TRAY_OKAY if icon._devices_info else _icons.TRAY_ATTENTION
+		icon.set_from_icon_name(tray_icon_name)
 
-	_icon_after_attention = None
+
+	def _update_menu_icon(image_widget, icon_name):
+		image_widget.set_from_icon_name(icon_name, _MENU_ICON_SIZE)
+
+
+	_icon_before_attention = None
 
 	def _blink(icon, count):
-		global _icon_after_attention
+		global _icon_before_attention
 		if count % 2:
 			icon.set_from_icon_name(_icons.TRAY_ATTENTION)
 		else:
-			icon.set_from_icon_name(_icon_after_attention)
+			icon.set_from_icon_name(_icon_before_attention)
 
 		if count > 0:
 			GLib.timeout_add(1000, _blink, icon, count - 1)
 
-	def attention(icon):
-		global _icon_after_attention
-		if _icon_after_attention is None:
-			_icon_after_attention = icon.get_icon_name()
+	def attention(icon, reason=None):
+		global _icon_before_attention
+		if _icon_before_attention is None:
+			_icon_before_attention = icon.get_icon_name()
 			GLib.idle_add(_blink, icon, 9)
 
 #
@@ -142,6 +251,10 @@ except ImportError:
 #
 
 def _generate_tooltip_lines(devices_info):
+	if not devices_info:
+		yield '<b>%s</b>: no receivers' % NAME
+		return
+
 	yield '<b>%s</b>' % NAME
 	yield ''
 
@@ -165,30 +278,26 @@ def _generate_tooltip_lines(devices_info):
 		yield ''
 
 
-def _generate_icon_name(icon):
-	if not icon._devices_info:
-		return _icons.TRAY_INIT
+def _pick_device_with_lowest_battery(devices_info):
+	if not devices_info:
+		return None
 
-	battery_status = None
-	battery_level = 1000
+	picked = None
+	picked_level = 1000
 
-	for _, serial, name, _, status in icon._devices_info:
-		if serial is None: # is receiver
+	for info in devices_info:
+		if info[1] is None: # is receiver/separator
 			continue
-		level = status.get(_status.BATTERY_LEVEL)
-		if level is not None and level < battery_level:
-			battery_status = status
-			battery_level = level
+		level = info[-1].get(_status.BATTERY_LEVEL)
+		if not picked or (level is not None and picked_level > level):
+			picked = info
+			picked_level = level or 0
 
-	if battery_status is None:
-		return _icons.TRAY_OKAY
+	if _log.isEnabledFor(_DEBUG):
+		_log.debug("picked device with lowest battery: %s", picked)
+
+	return picked
 
-	assert battery_level < 1000
-	charging = battery_status.get(_status.BATTERY_CHARGING)
-	icon_name = _icons.battery(battery_level, charging)
-	if icon_name and 'missing' in icon_name:
-		icon_name = None
-	return icon_name or _icons.TRAY_OKAY
 
 #
 #
@@ -219,22 +328,31 @@ def _add_device(icon, device):
 
 	# print ("status_icon: added", index, ":", device_info)
 
-	menu_item = Gtk.ImageMenuItem.new_with_label('    ' + device.name)
-	icon._menu.insert(menu_item, index)
+	# label_prefix = b'\xE2\x94\x84 '.decode('utf-8')
+	label_prefix = '   '
+
+	menu_item = Gtk.ImageMenuItem.new_with_label(label_prefix + device.name)
 	menu_item.set_image(Gtk.Image())
 	menu_item.show_all()
 	menu_item.connect('activate', icon._menu_activate_callback, device.receiver.path, icon)
 
+	icon._menu.insert(menu_item, index)
+
 	return index
 
 
 def _remove_device(icon, index):
-	# print ("remove device", index)
 	assert index is not None
-	del icon._devices_info[index]
+
 	menu_items = icon._menu.get_children()
 	icon._menu.remove(menu_items[index])
 
+	removed_device = icon._devices_info.pop(index)
+	global _picked_device
+	if _picked_device and _picked_device[1] == removed_device[1]:
+		# the current pick was unpaired
+		_picked_device = None
+
 
 def _add_receiver(icon, receiver):
 	device_info = (receiver.serial, None, receiver.name, None, None)
@@ -258,13 +376,15 @@ def _add_receiver(icon, receiver):
 def _remove_receiver(icon, receiver):
 	index = 0
 	found = False
+
+	# remove all entries in devices_info that match this receiver
 	while index < len(icon._devices_info):
 		rserial, _, _, _, _ = icon._devices_info[index]
-		# print ("remove receiver", index, rserial)
 		if rserial == receiver.serial:
 			found = True
 			_remove_device(icon, index)
 		elif found and rserial == '-':
+			# the separator after this receiver
 			_remove_device(icon, index)
 			break
 		else:
@@ -275,19 +395,19 @@ def _update_menu_item(icon, index, device_status):
 	menu_items = icon._menu.get_children()
 	menu_item = menu_items[index]
 
-	image = menu_item.get_image()
 	level = device_status.get(_status.BATTERY_LEVEL)
 	charging = device_status.get(_status.BATTERY_CHARGING)
-	image.set_from_icon_name(_icons.battery(level, charging), _MENU_ICON_SIZE)
-	image.set_sensitive(bool(device_status))
+	icon_name = _icons.battery(level, charging)
+
+	image_widget = menu_item.get_image()
+	image_widget.set_sensitive(bool(device_status))
+	_update_menu_icon(image_widget, icon_name)
 
 #
 #
 #
 
 def update(icon, device=None):
-	# print ("icon update", device, icon._devices_info)
-
 	if device is not None:
 		if device.kind is None:
 			# receiver
@@ -325,8 +445,8 @@ def update(icon, device=None):
 		menu_items[no_receivers_index].set_visible(not icon._devices_info)
 		menu_items[no_receivers_index + 1].set_visible(not icon._devices_info)
 
-	tooltip_lines = _generate_tooltip_lines(icon._devices_info)
-	tooltip = '\n'.join(tooltip_lines).rstrip('\n')
-	_update_icon(icon, _generate_icon_name(icon), tooltip)
+	global _picked_device
+	if not _picked_device:
+		_picked_device = _pick_device_with_lowest_battery(icon._devices_info)
 
-	# print ("icon updated", device, icon._devices_info)
+	_update_tray_icon(icon)