hide show_roster_on_startup from windows [no trayicon]

src/config.py

@@ -102,11 +102,14 @@ class Preferences_window:
 		st = gajim.config.get('show_roster_on_startup')
 		show_roster_on_startup_checkbutton = self.xml.get_widget(
 			'show_roster_on_startup_checkbutton')
-		if gajim.config.get('trayicon'): # allow it only when trayicon ON
-			show_roster_on_startup_checkbutton.set_active(st)
+		if os.name == 'nt':
+			show_roster_on_startup_checkbutton.set_no_show_all(True)
 		else:
-			show_roster_on_startup_checkbutton.set_sensitive(False)
-			show_roster_on_startup_checkbutton.set_active(st)
+			if gajim.config.get('trayicon'): # allow it only when trayicon ON
+				show_roster_on_startup_checkbutton.set_active(st)
+			else:
+				show_roster_on_startup_checkbutton.set_sensitive(False)
+				show_roster_on_startup_checkbutton.set_active(st)
 
 		#Save position
 		st = gajim.config.get('saveposition')

src/gtkgui.glade

@@ -5794,7 +5794,6 @@ Custom</property>
 
 			  <child>
 			    <widget class="GtkCheckButton" id="show_roster_on_startup_checkbutton">
-			      <property name="visible">True</property>
 			      <property name="can_focus">True</property>
 			      <property name="label" translatable="yes">Show roster window on startup</property>
 			      <property name="use_underline">True</property>

src/roster_window.py

@@ -1519,12 +1519,14 @@ class Roster_window:
 				gajim.config.get('y-position'))
 			self.window.resize(gajim.config.get('width'), \
 				gajim.config.get('height'))
+		
 		if gajim.config.get('show_roster_on_startup'):
 			self.window.show_all()
 		else:
 			if not gajim.config.get('trayicon'):
 				# cannot happen via GUI, but I put this incase user touches config
 				self.window.show_all() # without trayicon, he should see the roster!
+				gajim.config.set('show_roster_on_startup', True)
 			
 		self.groups = {}
 		self.contacts = {}