diff --git a/tools/rxbag/src/rxbag/__init__.py b/tools/rxbag/src/rxbag/__init__.py
index c1dfe674..7227f31a 100755
--- a/tools/rxbag/src/rxbag/__init__.py
+++ b/tools/rxbag/src/rxbag/__init__.py
@@ -36,5 +36,5 @@
 # Import rxbag main to be used by the $ROS_ROOT/bin/rxbag
 from rxbag_main import rxbag_main
 
-from bag_helper import BagHelper
+import bag_helper
 from message_view import MessageView, TimelineRenderer, TopicMessageView
diff --git a/tools/rxbag/src/rxbag/bag_helper.py b/tools/rxbag/src/rxbag/bag_helper.py
index 424ae4f6..d1274c57 100755
--- a/tools/rxbag/src/rxbag/bag_helper.py
+++ b/tools/rxbag/src/rxbag/bag_helper.py
@@ -34,22 +34,21 @@
 
 PKG = 'rxbag'
 import roslib; roslib.load_manifest(PKG)
-import rospy
-import rosbag
 
-import bisect
-import cPickle
-import math
-import os
-import sys
-import threading
 import time
 
-import numpy
+def stamp_to_str(t):      return time.strftime('%b %d %Y %H:%M:%S', time.localtime(t.to_sec())) + '.%03d' % (t.nsecs / 1000000)
+def get_topics(bag):      return sorted(set([c.topic for c in bag._get_connections()]))
+def get_start_stamp(bag): return min([index[ 0].time.to_sec() for index in bag._connection_indexes.values()])
+def get_end_stamp(bag):   return max([index[-1].time.to_sec() for index in bag._connection_indexes.values()])
 
-import util.progress_meter
+def get_topics_by_datatype(bag):
+    topics_by_datatype = {}
+    for c in bag._get_connections():
+        topics_by_datatype.setdefault(c.datatype, []).append(c.topic)
+    return topics_by_datatype
 
-class BagHelper:
-    @staticmethod
-    def stamp_to_str(t):
-        return time.strftime('%b %d %Y %H:%M:%S', time.localtime(t.to_sec())) + '.%03d' % (t.nsecs / 1000000)
+def get_datatype(bag, topic):
+    for c in bag._get_connections(topic):
+        return c.datatype
+    return None
diff --git a/tools/rxbag/src/rxbag/rxbag_main.py b/tools/rxbag/src/rxbag/rxbag_main.py
index 1a4a71fc..42327729 100755
--- a/tools/rxbag/src/rxbag/rxbag_main.py
+++ b/tools/rxbag/src/rxbag/rxbag_main.py
@@ -51,23 +51,20 @@ else:
     sys.exit(1)
 import wx
 import wx.lib.wxcairo
-
-# This is a crazy hack to get this to work on 64-bit systems
-if 'wxMac' in wx.PlatformInfo:
-    pass # Implement if necessary
-elif 'wxMSW' in wx.PlatformInfo:
-    pass # Implement if necessary
-elif 'wxGTK' in wx.PlatformInfo:
+if 'wxGTK' in wx.PlatformInfo:
+    # Workaround for 64-bit systems
     import ctypes
     gdkLib = wx.lib.wxcairo._findGDKLib()
     gdkLib.gdk_cairo_create.restype = ctypes.c_void_p
 
+import rosbag
+
 import util.base_frame
 import timeline
 
 class RxBagApp(wx.App):
     def __init__(self, input_files, options):
-        self.input_files = [input_files[0]]
+        self.input_files = input_files
         self.options     = options
 
         wx.App.__init__(self)
@@ -80,7 +77,19 @@ class RxBagApp(wx.App):
                 frame_title = 'rxbag - [%d bags]' % len(self.input_files)
     
             frame = util.base_frame.BaseFrame(None, 'rxbag', 'Timeline', title=frame_title)
-            timeline_panel = timeline.TimelinePanel(self.input_files, self.options, frame, -1)
+            timeline_panel = timeline.TimelinePanel(frame, -1)
+
+            if self.options.record:
+                connect_to_ros('rxbag', 3)
+                timeline_panel.timeline.record_bag()
+            else:
+                for input_file in self.input_files:
+                    try:
+                        bag = rosbag.Bag(input_file)
+                        timeline_panel.timeline.add_bag(bag)
+                    except Exception, ex:
+                        print >> sys.stderr, 'Error loading [%s]: %s' % (input_file, str(ex))
+
             frame.Show()
             self.SetTopWindow(frame)
             
@@ -91,48 +100,49 @@ class RxBagApp(wx.App):
         return True
 
 def connect_to_ros(node_name, init_timeout):
-    # Attempt to connect to master node
+    # Attempt to connect to master node                                                                                                                                
     class InitNodeThread(threading.Thread):
         def __init__(self):
             threading.Thread.__init__(self)
             self.setDaemon(True)
             self.inited = False
-            
+            self.init_cv = threading.Condition()
+
         def run(self):
-            rospy.loginfo('Attempting to connect to master node...')
+            rospy.loginfo('Master found.  Connecting...')
             rospy.init_node(node_name, anonymous=True, disable_signals=True)
+            self.init_cv.acquire()
             self.inited = True
+            self.init_cv.notify_all()
+            self.init_cv.release()
 
     try:
-        # Check whether ROS master is running
+        # Check whether ROS master is running                                                                                                                          
         master = rospy.get_master()
         master.getPid()
-        
-        # If so (i.e. no exception), attempt to initialize node
+
+        # If so (i.e. no exception), attempt to initialize node                                                                                                        
         init_thread = InitNodeThread()
+        init_thread.init_cv.acquire()
         init_thread.start()
-        time.sleep(init_timeout)
+        init_thread.init_cv.wait(init_timeout)
 
         if init_thread.inited:
             rospy.core.register_signals()
-            rospy.loginfo('Connected to master node.')
+            rospy.loginfo('Connected to ROS.')
         else:
-            rospy.logerr('Giving up. Couldn\'t connect to master node.')
+            rospy.logerr('Couldn\'t connect to ROS.  Running in unconnected mode.')
     except:
-        rospy.loginfo('Master not found.')
+        rospy.loginfo('Master not found.  Running in unconnected mode.')
 
 def rxbag_main():
     # Parse command line for input files and options
-    usage = "usage: %prog [options] BAG_FILE.bag"
+    usage = "usage: %prog [options] BAG_FILE1 [BAG_FILE2 ...]"
     parser = optparse.OptionParser(usage=usage)
-    #parser.add_option('-t', '--init-timeout', action='store', default=0.5, help='timeout in secs for connecting to master node')   
+    parser.add_option('-r', '--record', dest='record', default=False, action='store_true', help='record to a bag file')
     options, args = parser.parse_args(sys.argv[1:])
-    if len(args) == 0:
-        parser.print_help()
-        return
-    input_files = args[:]
 
-    #connect_to_ros('rxbag', options.init_timeout)
+    input_files = args[:]
 
     # Start application
     app = RxBagApp(input_files, options)
diff --git a/tools/rxbag/src/rxbag/status.py b/tools/rxbag/src/rxbag/status.py
index 0c31919e..3a8a6812 100755
--- a/tools/rxbag/src/rxbag/status.py
+++ b/tools/rxbag/src/rxbag/status.py
@@ -37,8 +37,8 @@ import roslib; roslib.load_manifest(PKG)
 
 import wx
 
+import bag_helper
 from util.layer import Layer
-from bag_helper import BagHelper
 
 class StatusLayer(Layer):
     def __init__(self, parent, title, timeline, x, y, width, height):
@@ -52,7 +52,7 @@ class StatusLayer(Layer):
 
         t = roslib.rostime.Time.from_sec(self.timeline.playhead)
 
-        s = BagHelper.stamp_to_str(t)
+        s = bag_helper.stamp_to_str(t)
         
         spd = self.timeline.play_speed
         spd_str = None
diff --git a/tools/rxbag/src/rxbag/timeline.py b/tools/rxbag/src/rxbag/timeline.py
index cf4c5c04..1097539f 100755
--- a/tools/rxbag/src/rxbag/timeline.py
+++ b/tools/rxbag/src/rxbag/timeline.py
@@ -39,61 +39,39 @@ import roslib; roslib.load_manifest(PKG)
 import rospy
 
 import rosbag
+import rosgraph.masterapi
 
 import bisect
 import collections
 import math
 import os
+import sys
 import threading
 import time
 
-import wx
 import cairo
+import wx
 
-from util.base_frame import BaseFrame
-from util.layer import Layer, LayerPanel
+import bag_helper
 import playhead
 import plugins
-import status
-
 from raw_view import RawView
+import status
+from util.base_frame import BaseFrame
+from util.layer import Layer, LayerPanel
 
 class TimelinePanel(LayerPanel):
-    def __init__(self, input_files, options, *args, **kwargs):
+    def __init__(self, *args, **kwargs):
         LayerPanel.__init__(self, *args, **kwargs)
-        
-        self.bag_files = {}
 
-        if not self._init_bag_files(input_files):
-            raise Exception('No valid bag files')
-
-        self._create_controls(options)
+        self._create_controls()
         self._create_toolbar()
 
-    def _init_bag_files(self, input_files):
-        unindexed = []
-        
-        for bag_path in input_files:
-            try:
-                bag_file = rosbag.Bag(bag_path)
-            except Exception, e:
-                print 'Error loading %s: %s' % (bag_path, e)
-                continue
-            
-            self.bag_files[bag_file] = bag_file
-                
-        if len(unindexed) + len(self.bag_files) == 0:
-            return False
-
-        return True
-
-    def _create_controls(self, options):
+    def _create_controls(self):
         (width, height) = self.GetParent().GetClientSize()
 
         x, y = 5, 19
-
         self.timeline = Timeline(self, 'Timeline', x, y, width - x, height - y)
-        self.timeline.set_bag_files(self.bag_files)
 
         self.status = status.StatusLayer(self, 'Status', self.timeline, self.timeline.x, 4, 300, 16)
 
@@ -139,14 +117,68 @@ class TimelinePanel(LayerPanel):
 
         tb.Realize()
 
+class SubscriberHelper(object):
+    def __init__(self, timeline, topic, pytype):
+        self.timeline   = timeline
+        self.subscriber = rospy.Subscriber(topic, pytype, self.callback)
+        self.topic      = topic
+        self.pytype     = pytype
+        
+        self.last_update = time.time()
+
+    def callback(self, msg):
+        with self.timeline._bag_lock:
+            self.timeline.bag_file.write(self.topic, msg)
+            
+        self.timeline.invalidated_caches.add(self.topic)
+        
+        now = time.time()
+        if now - self.last_update > 0.1:
+            wx.CallAfter(self.timeline.invalidate)
+            self.last_update = now
+
+class MasterCheckThread(threading.Thread):
+    def __init__(self, timeline, period=5):
+        threading.Thread.__init__(self)
+        
+        self.timeline = timeline
+        self.period   = period
+        
+        self.subscriber_helpers = {}
+        
+        self.failed_topics = set()
+        
+        self.start()
+        
+    def run(self):
+        master = rosgraph.masterapi.Master('rxbag')
+        
+        while True:
+            # Subscribe to any new topics
+            for topic, datatype in master.getPublishedTopics(''):
+                if topic not in self.subscriber_helpers and topic not in self.failed_topics:
+                    print 'Found new topic: %s [%s]' % (topic, datatype)
+                    
+                    try:
+                        pytype = roslib.message.get_message_class(datatype)
+                        self.subscriber_helpers[topic] = SubscriberHelper(self.timeline, topic, pytype)
+                    except Exception, ex:
+                        print >> sys.stderr, 'Error subscribing to %s (ignoring): %s' % (topic, str(ex))
+                        self.failed_topics.add(topic)
+
+            # Wait a while
+            time.sleep(self.period)
+
 class Timeline(Layer):
     name = 'Timeline'
     
     def __init__(self, parent, title, x, y, width, height):
         Layer.__init__(self, parent, title, x, y, width, height)
 
-        self.bag_files = {}
-        self.bag_file  = None
+        self._bag_lock = threading.Lock()
+
+        self.bags = []
+        self.bag_file = None  # @todo: remove
 
         ## Rendering parameters
 
@@ -221,6 +253,8 @@ class Timeline(Layer):
 
                 self.timeline  = timeline
                 self.stop_flag = False
+                
+                self.start()
 
             def run(self):
                 self.last_frame, self.last_playhead = None, None
@@ -258,67 +292,71 @@ class Timeline(Layer):
 
         self.play_speed = 0.0
 
-        self.play_thread = PlayThread(self)
-        self.play_thread.start()
-        
         self.message_history_cache = {}
+        self.invalidated_caches = set()
+
+        self.play_thread         = PlayThread(self)
+        
+        self.master_check_thread = None
+        
+    ###
+
+    def record_bag(self):
+        self.master_check_thread = MasterCheckThread(self)
+
+        self.bag_file = rosbag.Bag('rxbag.bag', 'w')
+
+    def add_bag(self, bag):
+        self.bags.append(bag)
+        
+        self.bag_file = bag
 
     @property
     def start_stamp(self):
-        return self.get_start_stamp(self.bag_file)
+        with self._bag_lock:
+            return bag_helper.get_start_stamp(self.bag_file)
 
     @property
     def end_stamp(self):
-        return self.get_end_stamp(self.bag_file)
+        with self._bag_lock:
+            return bag_helper.get_end_stamp(self.bag_file)
 
     @property
     def topics(self):
-        return sorted(set([c.topic for c in self.bag_file._get_connections()]))
+        with self._bag_lock:
+            return bag_helper.get_topics(self.bag_file)
 
-    def get_start_stamp(self, bag):
-        return min([index[0].time.to_sec() for index in bag._connection_indexes.values()])
-
-    def get_end_stamp(self, bag):
-        return max([index[-1].time.to_sec() for index in bag._connection_indexes.values()])
-
-    def get_topics_by_datatype(self):
-        topics_by_datatype = {}
-        for c in self.bag_file._get_connections():
-            topics_by_datatype.setdefault(c.datatype, []).append(c.topic)
-        return topics_by_datatype
+    @property
+    def topics_by_datatype(self):
+        with self._bag_lock:
+            return bag_helper.get_topics_by_datatype(self.bag_file)
 
     def get_datatype(self, topic):
-        for c in self.bag_file._get_connections(topic):
-            return c.datatype
+        with self._bag_lock:
+            return bag_helper.get_datatype(self.bag_file, topic)
+
+    def get_connections(self, topic):
+        with self._bag_lock:
+            return list(self.bag_file._get_connections(topic))
+
+    def get_entry(self, t, topic):
+        with self._bag_lock:
+            return self.bag_file._get_entry(t, self.bag_file._get_connections(topic))
+
+    def get_entries(self, connections, start_time, end_time):
+        with self._bag_lock:
+            return self.bag_file._get_entries(connections, start_time, end_time)
+
+    def read_message(self, position):
+        with self._bag_lock:
+            return self.bag_file._read_message(position)
 
     ##
 
     def on_close(self, event):
         self.play_thread.stop()
 
-    def save_layout(self):
-        user_config_dir = wx.StandardPaths.Get().GetUserConfigDir()
-        config_dir = os.path.join(user_config_dir, '.rxbag')
-        if not os.path.exists(config_dir):
-            os.mkdir(config_dir)
-        layout_file = os.path.join(config_dir, 'layout')
-        config = wx.Config(localFilename=layout_file)
-        
-        # TODO
-
-        #for i, view in enumerate(self.views):
-        #    config.Write('/Views/View%d' % (i + 1), view.__class__.__name__)
-        #config.Flush()
-
-    def load_layout(self):
-        user_config_dir = wx.StandardPaths.Get().GetUserConfigDir()
-        config_dir = os.path.join(user_config_dir, '.rxbag')
-        if not os.path.exists(config_dir):
-            return
-        layout_file = os.path.join(config_dir, 'layout')
-        config = wx.Config(localFilename=layout_file)
-        
-        # TODO
+    ### Views / listeners
 
     def add_view(self, topic, view):
         self.views.append(view)
@@ -328,9 +366,34 @@ class Timeline(Layer):
         self.remove_listener(topic, view)
         self.views.remove(view)
 
+    def add_listener(self, topic, listener):
+        self.listeners.setdefault(topic, []).append(listener)
+
+        self._update_message_view()
+        self.invalidate()
+
+    def remove_listener(self, topic, listener):
+        topic_listeners = self.listeners.get(topic)
+        if topic_listeners is not None and listener in topic_listeners:
+            topic_listeners.remove(listener)
+            if len(topic_listeners) == 0:
+                del self.listeners[topic]
+        self.invalidate()
+
+    ### Plugins
+
     def get_viewer_types(self, datatype):
         return [RawView] + self.viewer_types.get('*', []) + self.viewer_types.get(datatype, [])
     
+    def load_plugins(self):
+        for view, timeline_renderer, msg_types in plugins.load_plugins():
+            for msg_type in msg_types:
+                self.viewer_types.setdefault(msg_type, []).append(view)
+            if timeline_renderer is not None:
+                self.timeline_renderers[msg_type] = timeline_renderer(self)
+
+    ### Timeline renderers
+
     def get_renderers(self):
         renderers = []
 
@@ -342,19 +405,6 @@ class Timeline(Layer):
                 
         return renderers
 
-    def load_plugins(self):
-        for view, timeline_renderer, msg_types in plugins.load_plugins():
-            for msg_type in msg_types:
-                self.viewer_types.setdefault(msg_type, []).append(view)
-            if timeline_renderer is not None:
-                self.timeline_renderers[msg_type] = timeline_renderer(self)
-
-    def set_bag_files(self, bag_files):
-        self.bag_files = bag_files
-        
-        # todo: handle multiple bags
-        self.bag_file = list(self.bag_files)[0]
-
     def is_renderer_active(self, topic):
         return topic in self.rendered_topics
 
@@ -386,19 +436,7 @@ class Timeline(Layer):
         self.invalidate()
         self.parent.playhead.invalidate()
 
-    def add_listener(self, topic, listener):
-        self.listeners.setdefault(topic, []).append(listener)
-
-        self.update_message_view()
-        self.invalidate()
-
-    def remove_listener(self, topic, listener):
-        topic_listeners = self.listeners.get(topic)
-        if topic_listeners is not None and listener in topic_listeners:
-            topic_listeners.remove(listener)
-            if len(topic_listeners) == 0:
-                del self.listeners[topic]
-        self.invalidate()
+    ###
 
     @property
     def history_bottom(self):
@@ -411,7 +449,7 @@ class Timeline(Layer):
     def _set_status(self, status):
         self.parent.GetParent().SetStatusText(str(status))
 
-    ## Navigation
+    ### Navigation
 
     def navigate_play(self): self.play_speed = 1.0
     def navigate_stop(self): self.play_speed = 0.0
@@ -439,7 +477,7 @@ class Timeline(Layer):
     def navigate_start(self): self.set_playhead(self.start_stamp)
     def navigate_end(self):   self.set_playhead(self.end_stamp)
 
-    ## View port
+    ### View port
 
     def reset_timeline(self):
         self.reset_zoom() 
@@ -460,7 +498,11 @@ class Timeline(Layer):
         self.invalidate()
 
     def reset_zoom(self):
-        self.set_timeline_view(self.start_stamp, self.end_stamp)
+        start_stamp, end_stamp = self.start_stamp, self.end_stamp
+        if end_stamp - start_stamp < 5.0:
+            end_stamp = start_stamp + 5.0
+        
+        self.set_timeline_view(start_stamp, end_stamp)
 
     def zoom_in(self):  self.zoom_timeline(0.5)
     def zoom_out(self): self.zoom_timeline(2.0)
@@ -507,11 +549,11 @@ class Timeline(Layer):
             
             self.playhead_positions = {}
             for topic in self.topics:
-                entry = self.bag_file._get_entry(playhead_time, self.bag_file._get_connections(topic))
+                entry = self.get_entry(playhead_time, topic)
                 if entry:
                     self.playhead_positions[topic] = entry.position
 
-            self.update_message_view()
+            self._update_message_view()
 
             self.parent.status.invalidate()
             self.parent.playhead.update_position()
@@ -524,7 +566,7 @@ class Timeline(Layer):
         self.resize(w - self.x, h - self.y)   # resize layer to fill client area
 
     def paint(self, dc):
-        if len(self.topics) == 0:
+        if not self.bag_file or len(self.topics) == 0:
             return
 
         if self.stamp_left is None:
@@ -713,6 +755,27 @@ class Timeline(Layer):
             else:
                 self._draw_topic_history(dc, topic)
 
+    def _update_message_cache(self, topic):
+        if topic not in self.message_history_cache:
+            # Don't have any cache of messages in this topic
+            start_time = roslib.rostime.Time.from_sec(max(0.0, self.start_stamp))
+            topic_cache = []
+            self.message_history_cache[topic] = topic_cache
+        else:
+            # Check if the cache has been invalidated
+            if topic not in self.invalidated_caches:
+                return
+            
+            topic_cache = self.message_history_cache[topic]               
+            start_time = roslib.rostime.Time.from_sec(max(0.0, topic_cache[-1]))
+        
+        end_time = roslib.rostime.Time.from_sec(max(0.0, self.end_stamp))
+
+        for entry in self.get_entries(self.get_connections(topic), start_time, end_time):
+            topic_cache.append(entry.time.to_sec())
+
+        self.invalidated_caches.remove(topic)
+
     def _draw_topic_history(self, dc, topic):
         """
         Draw boxes to show message regions on timelines.
@@ -722,10 +785,7 @@ class Timeline(Layer):
         msg_y      = y + 1
         msg_height = h - 1
 
-        # Get all the connections on this topic
-        connections = list(self.bag_file._get_connections(topic))
-
-        datatype = connections[0].datatype
+        datatype = self.get_datatype(topic)
 
         # Get the renderer and the message combine interval
         renderer = None
@@ -736,15 +796,10 @@ class Timeline(Layer):
                 msg_combine_interval = self.map_dx_to_dstamp(renderer.msg_combine_px)
         if msg_combine_interval is None:
             msg_combine_interval = self.map_dx_to_dstamp(self.default_msg_combine_px)
-            
-        if topic not in self.message_history_cache:
-            start_time = roslib.rostime.Time.from_sec(max(0.0, self.start_stamp))
-            end_time   = roslib.rostime.Time.from_sec(max(0.0, self.end_stamp))
-            all_stamps = list(entry.time.to_sec() for entry in self.bag_file._get_entries(connections, start_time, end_time))
-            
-            self.message_history_cache[topic] = all_stamps
-        else:
-            all_stamps = self.message_history_cache[topic]
+
+        self._update_message_cache(topic)
+        
+        all_stamps = self.message_history_cache[topic]
 
         start_index = bisect.bisect_left(all_stamps, self.stamp_left)
         end_index   = bisect.bisect_left(all_stamps, self.stamp_right)
@@ -842,8 +897,7 @@ class Timeline(Layer):
         dc.line_to(x + w + 1, y + 2)
         dc.stroke()
 
-    def map_dx_to_dstamp(self, dx):
-        return float(dx) * (self.stamp_right - self.stamp_left) / self.history_width
+    ### Pixel location <-> timestamp
 
     def map_x_to_stamp(self, x, clamp_to_visible=True):
         fraction = float(x - self.history_left) / self.history_width
@@ -856,8 +910,8 @@ class Timeline(Layer):
 
         return max(0.0, self.stamp_left + fraction * (self.stamp_right - self.stamp_left))
 
-    def map_dstamp_to_dx(self, dstamp):
-        return (float(dstamp) * self.history_width) / (self.stamp_right - self.stamp_left)
+    def map_dx_to_dstamp(self, dx):
+        return float(dx) * (self.stamp_right - self.stamp_left) / self.history_width
 
     def map_stamp_to_x(self, stamp, clamp_to_visible=True):
         fraction = (stamp - self.stamp_left) / (self.stamp_right - self.stamp_left)
@@ -867,9 +921,10 @@ class Timeline(Layer):
 
         return self.history_left + fraction * self.history_width
 
-    ### Control
+    def map_dstamp_to_dx(self, dstamp):
+        return (float(dstamp) * self.history_width) / (self.stamp_right - self.stamp_left)
 
-    # Mouse events
+    ### Mouse events
 
     def on_left_down(self, event):
         self.clicked_pos = event.GetPosition()
@@ -893,6 +948,9 @@ class Timeline(Layer):
         if not self.contains(*self.clicked_pos):
             return
 
+        if not self.bag_file:
+            return
+
         self.parent.PopupMenu(TimelinePopupMenu(self.parent, self), self.clicked_pos)
 
     def on_mousewheel(self, event):
@@ -934,17 +992,10 @@ class Timeline(Layer):
             self.set_playhead(self.map_x_to_stamp(x))
 
             self.clicked_pos = mouse_pos
-            
-    ##
-    
-    def load_msg_by_stamp(self, topic, stamp):
-        index = topic.find_stamp_index(stamp)
-        if not index:
-            return None
 
-        pos = topic.msg_positions[index][1]
+    ###
 
-    def update_message_view(self):
+    def _update_message_view(self):
         if not self.playhead_positions:
             return
 
@@ -954,7 +1005,7 @@ class Timeline(Layer):
                 playhead_position = self.playhead_positions[topic]
                 if playhead_position is not None:
                     # Load the message
-                    msgs[topic] = self.bag_file._read_message(playhead_position)
+                    msgs[topic] = self.read_message(playhead_position)
                     continue
 
             msgs[topic] = None
@@ -979,6 +1030,31 @@ class Timeline(Layer):
                     except wx.PyDeadObjectError:
                         self.remove_listener(topic, listener)
 
+    ### Layout management
+
+    def save_layout(self):
+        user_config_dir = wx.StandardPaths.Get().GetUserConfigDir()
+        config_dir = os.path.join(user_config_dir, '.rxbag')
+        if not os.path.exists(config_dir):
+            os.mkdir(config_dir)
+        layout_file = os.path.join(config_dir, 'layout')
+        config = wx.Config(localFilename=layout_file)
+        
+        # TODO
+        #for i, view in enumerate(self.views):
+        #    config.Write('/Views/View%d' % (i + 1), view.__class__.__name__)
+        #config.Flush()
+
+    def load_layout(self):
+        user_config_dir = wx.StandardPaths.Get().GetUserConfigDir()
+        config_dir = os.path.join(user_config_dir, '.rxbag')
+        if not os.path.exists(config_dir):
+            return
+        layout_file = os.path.join(config_dir, 'layout')
+        config = wx.Config(localFilename=layout_file)
+        
+        # TODO
+
 class TimelinePopupMenu(wx.Menu):
     """
     Timeline popup menu.  Allows user to manipulate the timeline view, and open new message views.
@@ -1043,7 +1119,7 @@ class TimelinePopupMenu(wx.Menu):
         self.view_datatype_menu = wx.Menu()
         self.AppendSubMenu(self.view_datatype_menu, 'View (by datatype)...', 'View message detail')
 
-        topics_by_datatype = self.timeline.get_topics_by_datatype()
+        topics_by_datatype = self.timeline.topics_by_datatype
         
         for datatype in sorted(topics_by_datatype):
             # View... / datatype