=== modified file 'Lib/idlelib/PyShell.py'
--- Lib/idlelib/PyShell.py	2009-01-27 00:28:36 +0000
+++ Lib/idlelib/PyShell.py	2009-03-11 15:46:53 +0000
@@ -303,13 +303,17 @@
         })
 
 class ModifiedUndoDelegator(UndoDelegator):
-    "Extend base class: forbid insert/delete before the I/O mark"
+    "Extend base class: redirects inser/delete after the I/O mark"
 
     def insert(self, index, chars, tags=None):
         try:
-            if self.delegate.compare(index, "<", "iomark"):
-                self.delegate.bell()
-                return
+            if self.delegate.compare(index, "<", "iomark"): 
+                try:            # improved behavior
+                    text = self.delegate.delegate.delegate      
+                    text.mark_set("insert", "end-1c")           
+                except:         # on error, default to old behavior
+                    self.delegate.bell()
+                    return
         except TclError:
             pass
         UndoDelegator.insert(self, index, chars, tags)
@@ -814,6 +818,10 @@
         text.bind("<<open-stack-viewer>>", self.open_stack_viewer)
         text.bind("<<toggle-debugger>>", self.toggle_debugger)
         text.bind("<<toggle-jit-stack-viewer>>", self.toggle_jit_stack_viewer)
+        text.bind("<<cmd-history-prev>>", self.cmd_history_prev);     
+        text.bind("<<cmd-history-next>>", self.cmd_history_next);   
+        text.event_add("<<cmd-history-prev>>", "<Key-Up>");         
+        text.event_add("<<cmd-history-next>>", "<Key-Down>");       
         self.color = color = self.ColorDelegator()
         self.per.insertfilter(color)
         if use_subprocess:
@@ -853,6 +861,16 @@
     endoffile = False
     closing = False
 
+    def cmd_history_prev(self, event):    
+        if self.text.compare('insert', ">=", "iomark"):
+            self.history.history_prev(event)
+            return "break"
+
+    def cmd_history_next(self, event):  
+        if self.text.compare('insert', ">=", "iomark"):
+            self.history.history_next(event)
+            return "break"
+
     def set_warning_stream(self, stream):
         global warning_stream
         warning_stream = stream