Tkinter on OS X generates excessive event on non-US input sequence

Hi,
I've found that Tkinter on Mac OS X somehow incorrectly works with events when bound sequence hit on non-US keyboard layout.
I use Russian keyboard layout along with English and I'm trying now to arrange Undo/Redo shortcuts to work correctly independent of layout. Under Linux everything works fine from the box. Under OS X it seems like a bug and when I hit <Command-Cyrillic_ya> which is the same physical keys as <Command-z> tkinter sends excessive KeyPress event.
Here is the test code.
================
from tkinter import *

class TkExample(Frame):
    def __init__(self, parent):
        Frame.__init__(self, parent)
        self.pack()
        text = Text(self)
        text.pack()
        text.bind('<KeyPress>', self.on_kp)
        text.bind('<<Undo>>', self.on_undo)

    def on_kp(self, event):
        print('CHAR:', event.char)

    def on_undo(self, event):
        print('UNDO')


if __name__ == '__main__':
    root = Tk()
    TkExample(root)
    root.mainloop()
================

When I run the app and hit <Command-z> I get this output:
CHAR:
UNDO

But if I hit <Command-Cyrillic_ya> I see this:
CHAR:  
CHAR: z
UNDO

Under Linux in both cases I get the same output (1).

Can anyone explain this? Maybe this is not a bug?

-- 
Alexander Uvizhev
[email protected]