diff --git a/Tools/idle/Bindings.py b/Tools/idle/Bindings.py
index 85ae564..4138d26 100644
--- a/Tools/idle/Bindings.py
+++ b/Tools/idle/Bindings.py
@@ -109,6 +109,7 @@
     
     ("debug", "Go to line from traceback", None, "<<goto-traceback-line>>"),
     ("debug", "Open stack viewer", None, "<<open-stack-viewer>>"),
+    ("debug", "Toggle debugger", None, "<<toggle-debugger>>"),
     
     # Help menu
     
diff --git a/Tools/idle/Debugger.py b/Tools/idle/Debugger.py
new file mode 100644
index 0000000..3a16a12
--- /dev/null
+++ b/Tools/idle/Debugger.py
@@ -0,0 +1,92 @@
+import os
+import bdb
+import traceback
+from Tkinter import *
+
+
+class Debugger(bdb.Bdb):
+    
+    def __init__(self, pyshell):
+        bdb.Bdb.__init__(self)
+        self.pyshell = pyshell
+        self.make_gui()
+    
+    def close(self):
+        self.top.destroy()
+
+    def user_line(self, frame):
+        self.interaction(frame)
+
+    def user_return(self, frame, rv):
+        # XXX show rv?
+        self.interaction(frame)
+
+    def user_exception(self, frame, info):
+        self.interaction(frame, info)
+    
+    def make_gui(self):
+        pyshell = self.pyshell
+        self.flist = pyshell.flist
+        self.root = root = pyshell.root
+        self.top = top = Toplevel(root)
+        self.bframe = bframe = Frame(top)
+        self.bframe.pack()
+        self.buttons = bl = []
+        self.bcont = b = Button(bframe, text="Go", command=self.cont)
+        bl.append(b)
+        self.bstep = b = Button(bframe, text="Step into", command=self.step)
+        bl.append(b)
+        self.bnext = b = Button(bframe, text="Step over", command=self.next)
+        bl.append(b)
+        self.bret = b = Button(bframe, text="Step out", command=self.ret)
+        bl.append(b)
+        for b in bl:
+            b.configure(state="disabled")
+            b.pack(side="left")
+        self.status = Label(top)
+        self.status.pack()
+    
+    def interaction(self, frame, info=None):
+        self.frame = frame
+        code = frame.f_code
+        file = code.co_filename
+        lineno = frame.f_lineno
+        message = "file=%s, name=%s, line=%s" % (file, code.co_name, lineno)
+        if info:
+            type, value, tb = info
+            m1 = "%s" % str(type)
+##            if value is not None:
+##                try:
+##                    m1 = "%s: %s" % (m1, str(value))
+##                except:
+##                    pass
+            message = "%s\n%s" % (message, m1)
+        self.status.configure(text=message)
+        if file[:1] + file[-1:] != "<>" and os.path.exists(file):
+            edit = self.flist.open(file)
+            if edit:
+                edit.gotoline(lineno)
+        for b in self.buttons:
+            b.configure(state="normal")
+        self.top.tkraise()
+        self.root.mainloop()
+        for b in self.buttons:
+            b.configure(state="disabled")
+        self.status.configure(text="")
+        self.frame = None
+    
+    def cont(self):
+        self.set_continue()
+        self.root.quit()
+        
+    def step(self):
+        self.set_step()
+        self.root.quit()
+    
+    def next(self):
+        self.set_next(self.frame)
+        self.root.quit()
+    
+    def ret(self):
+        self.set_return(self.frame)
+        self.root.quit()
diff --git a/Tools/idle/PyShell.py b/Tools/idle/PyShell.py
index 74f8f8a..4cabc3e 100644
--- a/Tools/idle/PyShell.py
+++ b/Tools/idle/PyShell.py
@@ -20,6 +20,7 @@
       
     def fixedwindowsmenu(self, wmenu):
         wmenu.add_command(label="Python Shell", command=self.flist.open_shell)
+        wmenu.add_separator()
 
 
 class PyShellFileList(FileList):
@@ -138,12 +139,24 @@
             if key[:1] + key[-1:] != "<>":
                 del c[key]
 
+    debugger = None
+    
+    def setdebugger(self, debugger):
+        self.debugger = debugger
+    
+    def getdebugger(self):
+        return self.debugger
+
     def runcode(self, code):
         # Override base class method
+        debugger = self.debugger
         try:
             self.tkconsole.beginexecuting()
             try:
-                exec code in self.locals
+                if debugger:
+                    debugger.run(code, self.locals)
+                else:
+                    exec code in self.locals
             except SystemExit:
                 if tkMessageBox.askyesno(
                     "Exit?",
@@ -200,6 +213,7 @@
         text.bind("<<end-of-file>>", self.eof_callback)
         text.bind("<<goto-traceback-line>>", self.goto_traceback_line)
         text.bind("<<open-stack-viewer>>", self.open_stack_viewer)
+        text.bind("<<toggle-debugger>>", self.toggle_debugger)
 
         sys.stdout = PseudoFile(self, "stdout")
         sys.stderr = PseudoFile(self, "stderr")
@@ -229,6 +243,28 @@
     executing = 0
     canceled = 0
     endoffile = 0
+    
+    def toggle_debugger(self, event=None):
+        if self.executing:
+            tkMessageBox.showerror("Don't debug now",
+                "You can only toggle the debugger when idle",
+                master=self.text)
+            return "break"
+        db = self.interp.getdebugger()
+        if db:
+            db.close()
+            self.resetoutput()
+            self.console.write("[DEBUG OFF]\n")
+            sys.ps1 = ">>> "
+            self.showprompt()
+            self.interp.setdebugger(None)
+        else:
+            import Debugger
+            self.interp.setdebugger(Debugger.Debugger(self))
+            sys.ps1 = "[DEBUG ON]>>> "
+            self.showprompt()
+            self.top.tkraise()
+            self.text.focus_set()
 
     def beginexecuting(self):
         # Helper for ModifiedInterpreter