diff --git a/twander.py b/twander.py
index 7a8ff95..8f87134 100755
--- a/twander.py
+++ b/twander.py
@@ -4,7 +4,7 @@
 
 
 PROGNAME = "twander"
-RCSID = "$Id: twander.py,v 1.82 2002/11/25 23:06:48 tundra Exp $"
+RCSID = "$Id: twander.py,v 1.83 2002/11/26 18:58:30 tundra Exp $"
 VERSION = RCSID.split()[2]
 
 
@@ -13,6 +13,7 @@
 #----------------------------------------------------------#
 
 import getopt
+import mutex
 import os
 from socket import getfqdn
 from stat import *
@@ -143,6 +144,7 @@
 MB            = KB * KB   # 1 MB constant
 GB            = MB * KB   # 1 GB constant
 HOSTNAME      = getfqdn() # Full name of this host
+POLLINT       = 20        # Interval (ms) the poll routine should run
 REFRESHINT    = 2000      # Interval (ms) for automatic refresh
 
 
@@ -545,8 +547,20 @@
 
     def poll(self):
 
-        RefreshDirList()
-        self.DirList.after(REFRESHINT, self.poll)
+        # If new dir entered via mouse, force correct activation
+        if self.MouseNewDir:
+            self.DirList.activate(0)
+            self.MouseNewDir = FALSE
+
+        # See if its time to do a refresh
+
+        self.ElapsedTime += POLLINT
+        if self.ElapsedTime >= REFRESHINT:
+            RefreshDirList()
+            self.ElapsedTime = 0
+
+        # Setup next polling event
+        self.DirList.after(POLLINT, self.poll)
 
     # End of method 'twanderUI.poll()'
 
@@ -789,6 +803,8 @@
 #####
 
 def DirListHandler(event):
+    global UI
+    
     SAVE = TRUE
 
     # Get current selection.  If none, just return, otherwise process
@@ -832,15 +848,22 @@
         # Load UI with new directory
         LoadDirList(selected, save=SAVE)
 
-        # And always force selection of first item there.
-        # This guarantees a selection in the new
-        # directory context, so subsequent commands
-        # won't try to operate on an item selected in a
-        # previous directory
-        
-        KeySelTop(event)
+        # Indicate that we entered a new directory this way.
+        # This is a workaround for Tk madness.  When this
+        # routine is invoked via the mouse, Tk sets the
+        # activation *when this routine returns*.  That means
+        # that the activation set at the end of LoadDirList
+        # gets overidden.  We set this flag here so that
+        # we can subsequently do the right thing in our
+        # background polling loop.  Although this routine
+        # can also be invoked via a keyboard selection,
+        # we run things this way regardless since no harm
+        # will be done in the latter case.
 
-    # File selected with a double-click
+        UI.MouseNewDir = TRUE
+
+
+    # No, a *file* was selected with a double-click
     # If we're running Win32, use OS association to try and run it.
 
     elif OSNAME == 'nt':
@@ -901,6 +924,11 @@
     # And select new directory to visit
     UI.CurrentDir = newdir
 
+    # Wait until we have exclusive access to the widget
+
+    while not UI.DirListMutex.testandset():
+        pass
+
     # Clear out the old contents
     UI.DirList.delete(0,END)
 
@@ -911,11 +939,17 @@
     # And update the title to reflect changes
     UI.UpdateTitle(UIroot)
 
-    # Indicate that we've just entered a new directory
-    # so RefreshDirList does the right thing
+    # And always force selection of first item there.
+    # This guarantees a selection in the new
+    # directory context, so subsequent commands
+    # won't try to operate on an item selected in a
+    # previous directory
 
-    UI.NewDirEntered = TRUE
- 
+    KeySelTop(None)
+
+    #Release the lock
+    UI.DirListMutex.unlock()
+
 # End of 'LoadDirList():
 
 
@@ -1080,10 +1114,14 @@
 
 def RefreshDirList(*args):
 
+    # Wait until we have exclusive access to the widget
+
+    while not UI.DirListMutex.testandset():
+        pass
+
     # Get current selection and active
 
     sellist  = UI.DirList.curselection()
-
     active = UI.DirList.index(ACTIVE)
 
     # Save current scroll positions
@@ -1091,39 +1129,30 @@
     xs = UI.hSB.get()
     ys = UI.vSB.get()
 
-    # Get new directory listing
-    newlist = BuildDirList(UI.CurrentDir)
-
     # Clean out old listbox contents
     UI.DirList.delete(0,END)
 
     # Save the new directory information
-    UI.DirList.insert(0, *newlist)
+    UI.DirList.insert(0, *BuildDirList(UI.CurrentDir))
 
-    # First refresh after a new directory
-    # entered needs to force selection and
-    # active to 0.  This works around some
-    # strange Tkinter behavior.
-
-    if UI.NewDirEntered:
-        KeySelTop(args)
-        UI.NewDirEntered = FALSE
-
-    # Otherwise restore selections
-    else:
-        SetSelection(sellist, active)
+    # Restore selection(s)
+    SetSelection(sellist, active)
 
     # Restore scroll positions
 
     UI.DirList.xview(MOVETO, xs[0])
     UI.DirList.yview(MOVETO, ys[0])
-    
+
+    # Release the mutex
+    UI.DirListMutex.unlock()
 
 # End of 'RefreshDirList()
 
 
 #####
 # Set a particular selection, w/bounds checking
+# Note that 'selection' is passed as a string
+# but 'active' is passed as a number.
 #####
 
 def SetSelection(selection, active):
@@ -1149,7 +1178,6 @@
     # Now set the active entry
     UI.DirList.activate(active)
 
-
 # End of 'SetSelection()'
 
 
@@ -1236,8 +1264,14 @@
 # And current location
 UI.CurrentDir = ""
 
-# And the flag indicating new directory selected
-UI.NewDirEntered = FALSE
+# Need mutex to serialize on widget updates
+UI.DirListMutex = mutex.mutex()
+
+# Intialize the "new dir via mouse" flag
+UI.MouseNewDir = FALSE
+
+# Initialize the polling counter
+UI.ElapsedTime = 0
 
 # Start in detailed mode
 UI.SetDetailedView(TRUE)