diff --git a/client-barcode/display.py b/client-barcode/display.py
index 59ad56d..42422d7 100644
--- a/client-barcode/display.py
+++ b/client-barcode/display.py
@@ -1,74 +1,291 @@
 import serial
+from thread import start_new_thread, allocate_lock
+import time
+import threading
 
-
-
-class Display:
+class Display(threading.Thread):
 	def __init__(self,portname="/dev/ttyUSB0"):
+	        threading.Thread.__init__(self)
 		self.serialport=None
-		self.open_port(portname)
+		self.runme=True
+		self.idlemessage=None
+		self.portlock = allocate_lock()
+		self.portname=portname
+		self.brightness=5
+	        self.scroll_line1 = None
+		self.scroll_line2 = None
+		self.offset_line1 = 0
+		self.offset_line2 = 0
+		self.screensaver = Screensaver(self)
+		self.open_port()
 
 	def __del__(self):
+		if (not self.screensaver == None):
+			self.screensaver = None
+
 		if (not self.serialport == None):
 			self.serialport.close()
 			self.serialport=None
 
-	def open_port(self,portname):
-		self.serialport = serial.Serial(portname,9600,timeout=2,rtscts=True, dsrdtr=True)
-		print ("Initializing display:\n  %s\n" % self.serialport )
-		self.cmd_reset()
-		self.write("Hello world")
+	def open_port(self):
+
+		self.mutex_get()
+		try:
+			self.serialport = serial.Serial(self.portname,9600,timeout=2,rtscts=True, dsrdtr=True)
+			#print ("Initializing display on port:\n  %s\n" % self.serialport )
+			self.cmd_reset()
+			self.mutex_release()
+		except Exception as e:
+			#print ("Exception opening serial port '%s' for display\n" % self.portname)
+			#print ("Ignoring and trying to open it again later\n")
+			#print (e)
+			self.serialport = None
+			self.mutex_release()
+			pass
+		
+
+	#Helper-Function, scrolls text in a specific line.
+	def display_scroll_text(self,line,text):
+		if (line==1): #clear the line on invocation:
+			self.cmd("\x1f\x24\x01%c\x18" % chr(line) )
+			self.scroll_line1 = text
+			self.offset_line1=0
+		if (line==2): #clear the line on invocation:
+			self.cmd("\x1f\x24\x01%c\x18" % chr(line) )
+			self.scroll_line2 = text
+			self.offset_line2=0
+
+
+	def display_handle_scroll(self,line,text,offset):
+		if (text):
+			l = len(text)
+			if (l<21):
+				if (offset == 0):
+					self.cmd("\x1f\x24\x01%c%s" % (chr(line),text[offset:(20+offset)]))
+					offset=1
+			else:   
+				self.cmd("\x1f\x24\x01%c%s" % (chr(line),text[offset:(20+offset)]))
+				missing_chars=20+offset-l
+				if (missing_chars>0):
+					self.cmd(text[:missing_chars])
+				offset=((offset+1)%l)
+		else:   
+			offset=0        #reset offset
+		return offset
+
+
+	def run(self):
+		#print "Starting Display thread" 
+		self.screensaver.start()
+		while(self.runme):
+			#print("display thread loop\n")
+			self.mutex_get()
+			#print("display got mutex and handles scroll\n")
+			self.offset_line1 = self.display_handle_scroll(1,self.scroll_line1,self.offset_line1)
+	                self.offset_line2 = self.display_handle_scroll(2,self.scroll_line2,self.offset_line2)
+			self.mutex_release()
+			time.sleep(.5)
+		print "Exiting Display thread"
+
+
+
+
+	#Front-End Funtion to display a Screen
+	# with heading
+	def display_screen(self,title,message):
+		self.mutex_get()
+
+	        self.offset_line1=0
+	        self.offset_line2=0
+	        self.screensaver.idle_reset();
+	        self.cmd_brightness(5)
+
+	        if (len(title)<21):
+	                self.scroll_line1=None
+	                self.cmd("\x1f\x24\x01%c\x18%s" % (chr(1),'\xdb'*20) )
+	                if (len(title)<20):
+	                        pos=1+(20-len(title))/2
+	                else:
+	                        pos=1
+	                self.cmd("\x1f\x24%c%c%s" % (chr(pos),chr(1),title) )
+	        else:
+	                self.display_scroll_text(1,title)
+	
+	        self.display_scroll_text(2,message)
+		self.mutex_release()
+
+
+
 
 	def cmd_reset(self):
 		#reset the display
-		self.write("\x1b\x40")
+		self.cmd("\x1b\x40")
 
 	def cmd_cursor_show(self,on=True):
 		#show or hide the cursor
 		if (on): 
-			self.write("\x1f\x43\x01")
+			self.cmd("\x1f\x43\x01")
 		else:
-			self.write("\x1f\x43\x00")
+			self.cmd("\x1f\x43\x00")
 
 	def cmd_blink(self,rate=127):
-		self.write("\x1f\x45%c" % rate)
+		self.cmd("\x1f\x45%c" % chr(rate))
+
+
+	def cmd_brightness(self,level):
+		if (self.brightness==level):
+			return
+		#print("setting brightness to %i \n" %level)
+		if (level==0): #turn off:
+			self.cmd_display_on(False)	
+                        self.brightness = 0
+                        return
+		else:  
+			if (self.brightness==0): #turn on, then set wanted brightness:
+				self.cmd_display_on(True)	
+                        self.brightness = level
+                        self.cmd("\x1F\x58%c" % chr(level-1) )
 
 	def cmd_display_on(self,on=True):
 		# blink-command: 
 		# where the last value defines the blink rate, 
 		# with 0=always on, 255=always off
 		if (on):
+			if (not self.brightness==0):
+				return
+			#print("setting display to on: %s \n" % str(on))
 			self.cmd_blink(0)
+			self.brightness=5
 		else:
+			if (self.brightness==0):
+				return
+			#print("setting display to on: %s \n" % str(on))
 			self.cmd_blink(255)
+			self.brightness=0
 
 	def cmd_curmode_overwrite(self):
-		cmd_curmode(1)			
+		self.cmd_curmode(1)			
 
 	def cmd_curmode_vscroll(self):
-		cmd_curmode(2)			
+		self.cmd_curmode(2)			
 
 	def cmd_curmode_hscroll(self):
-		cmd_curmode(3)			
+		self.cmd_curmode(3)			
 
 	def cmd_curmode(self,val=2):
-		self.write("\x1f%c" % val)
+		self.cmd("\x1f%c" % chr(val))
 
 	def cmd_clear(self):
-		self.write("\x0c")
+		self.cmd("\x0c")
 
 	
 	def cmd_time(self):
 		# activate timer display in lower right corner.
 		# actual time has to be set via display_set_timer.
-		self.write("\x1f\x55")
+		self.cmd("\x1f\x55")
 
-	def cmd_time_set(self,h,m):
+	def cmd_time_set(self,h=None,m=None):
+		if (h==None or m==None):
+			now = time.localtime()
+			h=now.tm_hour
+			m=now.tm_min
 		# configures hour and minutes of the internal clock and
 		# displays the time in the lower right corner.
 		# turns off when something gets written into the line.
 		# two bytes have to follow with hour and minute
-		self.write("\x1F\x54%c%c" % (h,m) )
+		self.cmd("\x1F\x54%c%c" % (chr(h),chr(m)) )
+		self.cmd_curmode_hscroll() # makes the time more robust...
+
+	def cmd(self,text): #for commands: do not reset screensaver timeout
+		self.write(text,False)
+
+	def write(self,text,idle_reset=True): #for data: reset screensaver timeout
+		if (not self.serialport == None):
+			if (idle_reset):
+				self.screensaver.idle_reset();
+				self.scroll_line1=None
+				self.scroll_line2=None
+			self.serialport.write(text)	
+		else:
+			self.open_port()	
+
+	def setIdlemessage(self,text):
+		self.idlemessage=text
+	
+	def getIdlemessage(self):
+		return self.idlemessage
+
+	def mutex_get(self):
+		self.portlock.acquire()
+
+	def mutex_release(self):
+		self.portlock.release()
+
+	def terminate(self):
+		self.runme=False
+		if (not self.screensaver == None):
+			self.screensaver.terminate()
+			self.screensaver = None
+		
 
+import threading
+import time
+
+class Screensaver (threading.Thread):
+	def __init__(self,display):
+	        threading.Thread.__init__(self)
+		self.display=display
+		self.runme=True
+		self.idlecounter=0
+		self.timeout_dim=30
+		self.timeout_message=60
+		self.timeout_off=300
+		self.mutex = allocate_lock()
+	        threading.Thread.__init__(self)
+
+	def run(self):
+		#print "Starting Screensaver thread" 
+		while(self.runme):
+			self.mutex.acquire()
+			self._main_loop()
+			self.mutex.release()
+			time.sleep(.5)
+		#print "Exiting Screensaver thread"
+
+	def terminate(self):
+		self.runme = False
+
+
+	def idle_reset(self):
+		self.mutex.acquire()
+		self.idlecounter=0
+		self.display.cmd_brightness(5)
+		self.mutex.release()
+
+
+	def _main_loop(self):
+		if (self.idlecounter < self.timeout_off):
+			self.idlecounter+=1
+		if (self.idlecounter>=self.timeout_dim and self.idlecounter <= (self.timeout_dim+7)):
+			x = (8-( self.idlecounter - self.timeout_dim))/2
+			self.display.mutex_get()
+			self.display.cmd_brightness(1+x)
+			self.display.mutex_release()
+			return
+
+		if (self.idlecounter==self.timeout_message):
+			self.display.mutex_get()
+			self.display.cmd_time_set()
+			self.display.scroll_line1 = self.display.getIdlemessage()
+			self.display.mutex_release()
+			return
+
+		if (self.idlecounter==self.timeout_off):
+			self.display.mutex_get()
+                        self.display.cmd_display_on(False)
+			self.display.mutex_release()
+			return
+		
+	def __del__(self):
+		print("bye")
 
-	def write(self,text):
-		self.serialport.write(text)	
diff --git a/client-barcode/freitagskasse.py b/client-barcode/freitagskasse.py
index 8ffedd9..1c6159b 100644
--- a/client-barcode/freitagskasse.py
+++ b/client-barcode/freitagskasse.py
@@ -42,7 +42,6 @@ display_fifo = None
 scroll_line1 = None
 scroll_line2 = None
 
-idlemessage = None
 
 offset_line1 = 0
 offset_line2 = 0
@@ -56,158 +55,6 @@ SCREENSAVER_OFF     = 2* 10*60
 
 lock = allocate_lock()
 
-#Helper-Function, scrolls text in a specific line.
-def display_scroll_text(line,text):
-	global scroll_line1,scroll_line2
-	global offset_line1,offset_line2
-	lock.acquire()
-	if (line==1): #clear the line on invocation:
-		send_display("\x1f\x24\x01%c\x18" % chr(line) )
-		scroll_line1 = text
-		offset_line1=0
-	if (line==2): #clear the line on invocation:
-		send_display("\x1f\x24\x01%c\x18" % chr(line) )
-		scroll_line2 = text
-		offset_line2=0
-	lock.release()
-	
-
-def display_handle_scroll(line,text,offset):
-	if (text):
-		l = len(text)
-		if (l<21):
-			if (offset == 0):
-				send_display("\x1f\x24\x01%c%s" % (chr(line),text[offset:(20+offset)]))
-				offset=1
-		else:
-			send_display("\x1f\x24\x01%c%s" % (chr(line),text[offset:(20+offset)]))
-			missing_chars=20+offset-l
-			if (missing_chars>0):
-				send_display(text[:missing_chars])
-			offset=((offset+1)%l)
-	else:
-		offset=0	#reset offset
-	return offset
-
-
-def display_cmd_dim(x):
-	global brightness
-	if (brightness!=x):
-		if (x==0): #turn off:
-			send_display("\x1F\x45%c" % chr(255) )
-			brightness = x
-			return
-			
-		else:
-			if (brightness==0): #turn on, then set wanted brightness:
-				send_display("\x1F\x45%c" % chr(0) )
-			brightness = x
-			send_display("\x1F\x58%c" % chr(x-1) )
-
-
-def display_thread(x):
-	global scroll_line1,scroll_line2
-	global offset_line1,offset_line2
-	global screensaver
-	global idlemessage
-
-	offset_line1=0
-	offset_line2=0
-	while(True):
-		lock.acquire()
-
-		offset_line1 = display_handle_scroll(1,scroll_line1,offset_line1)
-		offset_line2 = display_handle_scroll(2,scroll_line2,offset_line2)
-
-		if (screensaver <= SCREENSAVER_OFF):
-			screensaver=screensaver+1
-
-		if ((screensaver >= SCREENSAVER_DIM) and (screensaver <= (SCREENSAVER_DIM+7))): #activate first stage of screensaver:
-			x = (8-( screensaver - SCREENSAVER_DIM))/2
-			display_cmd_dim(1+x)
-
-		if (screensaver == SCREENSAVER_TIMEOUT):
-			now = time.localtime()
-			send_display("\x0c\x1F\x54%c%c\x1f\x03" % (chr(now.tm_hour),chr(now.tm_min)));
-			if (scroll_line2):
-				scroll_line1=scroll_line2
-			else:
-				scroll_line1=idlemessage
-			scroll_line2=None
-			offset_line1=0
-			offset_line2=0				
-		
-		if (screensaver == SCREENSAVER_OFF):
-			display_cmd_dim(0)
-			
-		lock.release()
-		time.sleep(.5)
-
-
-def send_display(s):
-	global display_fifo
-	if not display_fifo:
-		try:
-			fd = os.open( "/tmp/display", os.O_WRONLY)
-			display_fifo = os.fdopen(fd,"w")
-		except OSError:
-			display_fifo = None
-			pass
-			return
-		except IOError:
-			display_fifo = None
-			pass
-			return
-	try:
-		display_fifo.write(s)
-		display_fifo.flush()
-	except IOError:
-		display_fifo = None
-		pass
-		return
-
-
-#Front-End Funtion to display a Screen
-# with heading
-def display_screen(title,message):
-	global scroll_line1,scroll_line2
-	global offset_line1,offset_line2
-	global screensaver
-
-	offset_line1=0
-	offset_line2=0
-	screensaver=0
-	display_cmd_dim(5)
-
-	if (len(title)<21):
-		scroll_line1=None
-		send_display("\x1f\x24\x01%c\x18%s" % (chr(1),'\xdb'*20) )
-		if (len(title)<20):
-			pos=1+(20-len(title))/2
-		else:
-			pos=1
-		send_display("\x1f\x24%c%c%s" % (chr(pos),chr(1),title) )
-	else:
-		display_scroll_text(1,title)
-
-	display_scroll_text(2,message)
-
-
-#Front-End function to send data to the display.
-def print_display(s):
-	global scroll_line1,scroll_line2
-	global offset_line1,offset_line2
-	global screensaver
-
-	lock.acquire()
-	screensaver=0
-	offset_line1=0
-	offset_line2=0
-	scroll_line1=None
-	scroll_line2=None
-	display_cmd_dim(5)
-	send_display(s)
-	lock.release()
 
 def clear():
 	os.system('clear')
@@ -328,7 +175,7 @@ class Status:
 		if self.logged_in():
 			print('Eingeloggt als:  %s%s%s' % (COLOR_SOME, self.login_name, COLOR_RESET))
 			print()
-			print_display('\x0cHallo %-14s' % (self.login_name[:13]+"!") )
+			myDisplay.write('\x0cHallo %-14s' % (self.login_name[:13]+"!") )
 			if self.transfers:
 				initial_command, initial_balance = self.transfers[0]
 
@@ -360,11 +207,11 @@ class Status:
 						mylabel="Pfand "+command.commodity_label()[:9]
 					if (mycmd==3):	
 						mylabel=("%-13s" % (command.commodity_label()[:13]))+"+P"
-					print_display('\x0b%-15s %4.2f' % (asciify(mylabel)[:15],abs(command.difference())));
-					print_display('\x0b\nSUMME: {%02i} %8.2f' % ((i-1),initial_balance - self.balance));
+					myDisplay.write('\x0b%-15s %4.2f' % (asciify(mylabel)[:15],abs(command.difference())));
+					myDisplay.write('\x0b\nSUMME: {%02i} %8.2f' % ((i-1),initial_balance - self.balance));
 				else:
-					print_display('\x0b%-15s %4.2f' % (command.label()[:15],abs(command.difference())));
-					print_display('\x0b\nSUMME: {%02i} %8.2f' % ((i-1),initial_balance - self.balance));
+					myDisplay.write('\x0b%-15s %4.2f' % (command.label()[:15],abs(command.difference())));
+					myDisplay.write('\x0b\nSUMME: {%02i} %8.2f' % ((i-1),initial_balance - self.balance));
 
 				if len(self.transfers) > 1:
 					show_total(self.balance - initial_balance, plus='+')
@@ -373,13 +220,13 @@ class Status:
 
 				if self.balance < 0:
 					warn_balance()
-					print_display('\x0b\nKonto: %5.2f!' % (self.balance) )
+					myDisplay.write('\x0b\nKonto: %5.2f!' % (self.balance) )
 					print()
 
 				print(COLOR_MUCH + 'Committen nicht vergessen.' + COLOR_RESET)
 			else:
 				print('Kontostand beträgt:  %s%.2f Euro%s' % (COLOR_MUCH, self.balance, COLOR_RESET))
-				display_screen("KONTOSTAND","%s: %.2f Euro" % (self.login_name,self.balance))
+				myDisplay.display_screen("KONTOSTAND","%s: %.2f Euro" % (self.login_name,self.balance))
 				if self.balance < 0:
 					print()
 					warn_balance()
@@ -387,7 +234,7 @@ class Status:
 			print(COLOR_MUCH + 'Bitte einloggen.' + COLOR_RESET)
 			print()
 			print('Scanne dazu deine ID-Karte mit dem Barcode-Leser.')
-			display_screen("LOGIN","Bitte scanne Deinen login-Token! *** ")
+			myDisplay.display_screen("LOGIN","Bitte scanne Deinen login-Token! *** ")
 		print()
 
 	def logged_in(self):
@@ -416,7 +263,7 @@ class Status:
 			try:
 				command.run(self.login_name)
 			except urllib2.HTTPError as e:
-				print_display('\x0cFEHLER: Server Error%20s' % str(e)[:20])
+				myDisplay.display_screen("Server error",'Server Error: %s' % str(e))
 				error_page('FEHLER bei Kommunikation mit Server "%s"' % str(e))
 				break
 			else:
@@ -499,11 +346,11 @@ class Status:
 				error_page(_PRODUCT_FIRST)
 				return
 			if prev.includes_deposit():
-				print_display('\x0cFEHLER: schon Pfand %20s' % prev.item_name()[:20])
+				myDisplay.write('\x0cFEHLER: schon Pfand %20s' % prev.item_name()[:20])
 				error_page('FEHLER: Pfand für Produkt "%s" bereits aktiviert' % prev.item_name())
 				return
 			if prev.deposit_value() <= 0:
-				print_display('\x0cFEHLER: Pfandfrei!  %20s' % prev.item_name()[:20])
+				myDisplay.write('\x0cFEHLER: Pfandfrei!  %20s' % prev.item_name()[:20])
 				error_page('FEHLER: Produkt "%s" hat kein Pfand' % prev.item_name())
 				return
 			before = prev.difference()
@@ -545,14 +392,14 @@ def print_prompt():
 
 
 def handle(line, status):
-	global idlemessage
 	if line == 'exit':
 		clear()
-		print_display("\x0c")
+		myDisplay.write("\x0c")
+		myDisplay.terminate()
 		sys.exit(0)
 
 	if status.logged_in():
-		idlemessage=" Comitten nicht vergessen! ***"
+		myDisplay.setIdlemessage(" Comitten nicht vergessen! ***")
 		if line in CODES:
 			call = CODES[line]
 			method = call[0]
@@ -563,15 +410,15 @@ def handle(line, status):
 				item = status.find(line)
 			except urllib2.HTTPError as e:
 				if e.code == 404:  # URL not found == item not found with REST
-					print_display('\x0cERROR: %13sCode ist unbekannt' % ( line[:13]))
+					myDisplay.display_screen("FEHLER","Code ist unbekannt: '%s'" % ( line[:23]))
 					error_page('FEHLER: Aktion oder Ware "%s" nicht bekannt' % line)
 				else:
-					print_display('\x0cERROR: Server Error%20s' % str(e)[:20])
+					myDisplay.display_screen("Server error",'%20s' % str(e)[:20])
 					error_page('FEHLER bei Kommunikation mit Server "%s"' % str(e))
 			else:
 				status.buy(item)
 	else:
-		idlemessage="Mir ist langweilig!"
+		myDisplay.setIdlemessage("Mir ist langweilig!")
 		try:
 			status.login(line)
 		except urllib2.HTTPError as e:
@@ -584,7 +431,7 @@ def handle(line, status):
 					pass
 
 				if item is None:
-					display_screen("FEHLER","Nutzer ist  unbekannt: '%s' *** " % line)
+					myDisplay.display_screen("FEHLER","Nutzer ist  unbekannt: '%s' *** " % line)
 
 					error_page('FEHLER: Produkt oder Nutzer "%s" nicht bekannt' % line,
 							hint_message='Ist in der WebApp unter "Einstellungen" ' \
@@ -592,8 +439,9 @@ def handle(line, status):
 							'als erlaubt markiert?')
 				else:
 					item_info_page(item)
+
 			else:
-				print_display('\x0cFEHLER: Server Error%20s' % str(e)[:20])
+				myDisplay.display_screen("FEHLER",'Server Error %20s' % str(e)[:20])
 				error_page('FEHLER bei Kommunikation mit Server "%s"' % str(e))
 		except urllib2.URLError as e:
 			error_page('FEHLER bei Kommunikation mit Server "%s"' % str(e))
@@ -615,21 +463,19 @@ def main():
 	global myDisplay
 
 	myDisplay = Display("/dev/ttyUSB0")
+	myDisplay.start()
 	myDisplay.cmd_reset()
+	myDisplay.cmd_cursor_show(False)
 
-	print_display("\x1b\x40\x1f\x43\x00")
-	start_new_thread(display_thread,(1,))
-
-	#display_scroll_text(1,"Line1: Text, dumm scrollend!")
-	#display_scroll_text(4,"Line2: Und hier Text, auch dumm scrollend!")
-	display_screen("HINWEIS","Herzlich willkommen bei der Freitagsrunde! *** ")
+	myDisplay.display_screen("HINWEIS","Herzlich willkommen bei der Freitagsrunde! *** ")
+	time.sleep(5)
 	while True:
 		clear()
 		status.dump()
 		print_prompt()
 		line = read_line(sys.stdin, timeout=3*60.0, timeout_func=status.logout)
 		if line:
-			print_display('\x0cBarcode:\n%20s' % line[:20])
+			myDisplay.write('\x0cBarcode:\n%20s' % line[:20])
 			handle(line, status)
 
 
@@ -637,5 +483,7 @@ if __name__ == '__main__':
 	try:
 		main()
 	except KeyboardInterrupt:
+		myDisplay.terminate()
+		myDisplay.write("\x1b\x40Goodbye!")
 		pass
-		print_display("\x1b\x40Goodbye!")
+