diff --git a/src/config.py b/src/config.py
index 9728577f7..3ad5b01eb 100644
--- a/src/config.py
+++ b/src/config.py
@@ -534,69 +534,12 @@ class PreferencesWindow:
 		gajim.interface.roster.change_roster_style(None)
 		gajim.interface.save_config()
 
-	# FIXME: Remove or implement for new window code
-	def merge_windows(self, kind):
-		for acct in gajim.connections:
-			# save buffers and close windows
-			buf1 = {}
-			buf2 = {}
-			saved_var = {}
-			windows = gajim.interface.instances[acct][kind]
-			jids = windows.keys()
-			for jid in jids:
-				window = windows[jid]
-				buf1[jid] = window.conversation_textviews[jid].get_buffer()
-				buf2[jid] = window.message_textviews[jid].get_buffer()
-				saved_var[jid] = window.save_var(jid)
-				window.window.destroy()
-			# open new tabbed chat windows
-			for jid in jids:
-				if kind == 'chats':
-					c = gajim.contacts.get_contact_with_highest_priority(acct, jid)
-					gajim.interface.roster.new_chat(c, acct)
-				if kind == 'gc':
-					gajim.interface.roster.new_room(jid, saved_var[jid]['nick'], acct)
-				window = windows[jid]
-				window.conversation_textviews[jid].set_buffer(buf1[jid])
-				window.message_textviews[jid].set_buffer(buf2[jid])
-				window.load_var(jid, saved_var[jid])
-
-	# FIXME: Remove or implement for new window code
-	def split_windows(self, kind):
-		for acct in gajim.connections:
-			# save buffers and close tabbed chat windows
-			buf1 = {}
-			buf2 = {}
-			saved_var = {}
-			windows = gajim.interface.instances[acct][kind]
-			jids = windows.keys()
-			if not 'tabbed' in jids:
-				continue
-			jids.remove('tabbed')
-			for jid in jids:
-				window = windows[jid]
-				buf1[jid] = window.conversation_textviews[jid].get_buffer()
-				buf2[jid] = window.message_textviews[jid].get_buffer()
-				saved_var[jid] = window.save_var(jid)
-			windows['tabbed'].window.destroy()
-			# open new tabbed chat windows
-			for jid in jids:
-				if kind == 'chats':
-					c = gajim.contacts.get_contact_with_highest_priority(acct, jid)
-					gajim.interface.roster.new_chat(c, acct)
-				if kind == 'gc':
-					gajim.interface.roster.new_room(jid, saved_var[jid]['nick'], acct)
-				window = windows[jid]
-				window.conversation_textviews[jid].set_buffer(buf1[jid])
-				window.message_textviews[jid].set_buffer(buf2[jid])
-				window.load_var(jid, saved_var[jid])
-
 	def on_one_window_type_combo_changed(self, widget):
 		active = widget.get_active()
 		config_type = common.config.opt_one_window_types[active]
 		gajim.config.set('one_message_window', config_type)
 		gajim.interface.save_config()
-		# FIXME: Update current windows? Meh
+		gajim.interface.msg_win_mgr.reconfig()
 
 	def apply_speller(self, kind):
 		for acct in gajim.connections:
diff --git a/src/message_window.py b/src/message_window.py
index 432a585b4..d075562a5 100644
--- a/src/message_window.py
+++ b/src/message_window.py
@@ -409,8 +409,9 @@ class MessageWindow:
 
 	def _on_notebook_switch_page(self, notebook, page, page_num):
 		old_no = notebook.get_current_page()
-		old_ctrl = self._widget_to_control(notebook.get_nth_page(old_no))
-		old_ctrl.set_control_active(False)
+		if old_no >= 0:
+			old_ctrl = self._widget_to_control(notebook.get_nth_page(old_no))
+			old_ctrl.set_control_active(False)
 		
 		new_ctrl = self._widget_to_control(notebook.get_nth_page(page_num))
 		new_ctrl.set_control_active(True)
@@ -706,6 +707,7 @@ class MessageWindowMgr:
 		for w in self.windows():
 			self.save_state(w)
 			w.window.hide()
+			w.window.destroy()
 
 	def save_state(self, msg_win):
 		if not gajim.config.get('saveposition'):
@@ -746,3 +748,35 @@ class MessageWindowMgr:
 			gajim.config.set(pos_y_key, y)
 			gajim.config.set(size_width_key, width)
 			gajim.config.set(size_height_key, height)
+
+	def reconfig(self):
+		for w in self._windows.values():
+			self.save_state(w)
+		# Map the mode to a int constant for frequent compares
+		mode = gajim.config.get('one_message_window')
+		if self.mode == common.config.opt_one_window_types.index(mode):
+			# No change
+			return
+		self.mode = common.config.opt_one_window_types.index(mode)
+
+		controls = []
+		for w in self._windows.values():
+			w.window.hide()
+			while w.notebook.get_n_pages():
+				page = w.notebook.get_nth_page(0)
+				ctrl = w._widget_to_control(page)
+				w.notebook.remove_page(0)
+				page.unparent()
+				controls.append(ctrl)
+			w.window.destroy()
+
+		for k in self._windows.keys():
+			del self._windows[k]
+		self._windows = {}
+
+		for ctrl in controls:
+			mw = self.get_window(ctrl.contact.jid)
+			if not mw:
+				mw = self.create_window(ctrl.contact, ctrl.account, ctrl.type_id)
+			ctrl.parent_win = mw
+			mw.new_tab(ctrl)