diff --git a/Lib/idlelib/configDialog.py b/Lib/idlelib/configDialog.py
index a45188b..2b13391 100644
--- a/Lib/idlelib/configDialog.py
+++ b/Lib/idlelib/configDialog.py
@@ -595,8 +595,9 @@
         listIndex=self.listBindings.index(ANCHOR)
         binding=self.listBindings.get(listIndex)
         bindName=binding.split()[0] #first part, up to first space
-        newKeys=GetKeysDialog(self,'Get New Keys',bindName)
-        print newKeys.result
+        currentKeySet=idleConf.CurrentKeys()
+        currentKeySequences=idleConf.GetKeys(currentKeySet).values()
+        newKeys=GetKeysDialog(self,'Get New Keys',bindName,currentKeySequences)
         if newKeys.result: #new keys were specified
             self.listBindings.delete(listIndex)
             self.listBindings.insert(listIndex,bindName+' - '+newKeys.result)
diff --git a/Lib/idlelib/keybindingDialog.py b/Lib/idlelib/keybindingDialog.py
index ef0fda9..0958578 100644
--- a/Lib/idlelib/keybindingDialog.py
+++ b/Lib/idlelib/keybindingDialog.py
@@ -6,7 +6,13 @@
 import string, os
 
 class GetKeysDialog(Toplevel):
-    def __init__(self,parent,title,action):
+    def __init__(self,parent,title,action,currentKeySequences):
+        """
+        action - string, the name of the virtual event these keys will be
+                 mapped to
+        currentKeys - list, a list of all key sequence lists currently mapped
+                 to virtual events, for overlap checking   
+        """
         Toplevel.__init__(self, parent)
         self.configure(borderwidth=5)
         self.resizable(height=FALSE,width=FALSE)
@@ -16,6 +22,7 @@
         self.protocol("WM_DELETE_WINDOW", self.Cancel)
         self.parent = parent
         self.action=action
+        self.currentKeySequences=currentKeySequences
         self.result=''
         self.keyString=StringVar(self)
         self.keyString.set('')
@@ -191,29 +198,6 @@
         apply(self.listKeysFinal.insert,
             (END,)+keys)
     
-    def KeysOk(self):
-        #simple validity check
-        keysOk=1
-        keys=self.keyString.get()
-        keys.strip()
-        finalKey=self.listKeysFinal.get(ANCHOR)
-        modifiers=self.GetModifiers()
-        if not keys: #no keys specified
-            tkMessageBox.showerror(title='Key Sequence Error',
-                    message='No keys specified.')
-            keysOk=0
-        elif not keys.endswith('>'): #no final key specified
-            tkMessageBox.showerror(title='Key Sequence Error',
-                    message='No final key specified.')
-            keysOk=0
-        elif (modifiers==['Shift']) and (finalKey not in self.functionKeys):
-            #shift alone is only a useful modifier with a function key
-            tkMessageBox.showerror(title='Key Sequence Error',
-                    message='Shift alone is only a useful modifier '+
-                            'when used with a function key.')
-            keysOk=0
-        return keysOk
-    
     def Ok(self, event=None):
         if self.KeysOk():
             self.result=self.keyString.get()
@@ -223,6 +207,39 @@
         self.result=''
         self.destroy()
     
+    def KeysOk(self):
+        #simple validity check
+        keysOk=1
+        keys=self.keyString.get()
+        keys.strip()
+        finalKey=self.listKeysFinal.get(ANCHOR)
+        modifiers=self.GetModifiers()
+        keySequence=keys.split()#make into a key sequence list for overlap check
+        if not keys: #no keys specified
+            tkMessageBox.showerror(title='Key Sequence Error',
+                    message='No keys specified.')
+            keysOk=0
+        elif not keys.endswith('>'): #no final key specified
+            tkMessageBox.showerror(title='Key Sequence Error',
+                    message='No final key specified.')
+            keysOk=0
+        elif (not modifiers) and (finalKey not in self.functionKeys):
+            #modifier required if not a function key
+            tkMessageBox.showerror(title='Key Sequence Error',
+                    message='No modifier key(s) specified.')
+            keysOk=0
+        elif (modifiers==['Shift']) and (finalKey not in self.functionKeys):
+            #shift alone is only a useful modifier with a function key
+            tkMessageBox.showerror(title='Key Sequence Error',
+                    message='Shift alone is only a useful modifier '+
+                            'when used with a function key.')
+            keysOk=0
+        elif keySequence in self.currentKeySequences: #keys combo already in use
+            tkMessageBox.showerror(title='Key Sequence Error',
+                    message='This key combination is already in use.')
+            keysOk=0
+        return keysOk
+    
 if __name__ == '__main__':
     #test the dialog
     root=Tk()
@@ -230,7 +247,7 @@
         #import aboutDialog
         #aboutDialog.AboutDialog(root,'About')
         keySeq=''
-        dlg=GetKeysDialog(root,'Get Keys','find-again')
+        dlg=GetKeysDialog(root,'Get Keys','find-again',[])
         print dlg.result
     Button(root,text='Dialog',command=run).pack()
     root.mainloop()