wxTextCtrl - copy and paste 65,000 characters of text into it only seems to hold 30,003

[abcd]

I have a wxTextCtrl:

wx.TextCtrl(self.myPanel, -1, "", style=wx.TE_MULTILINE)

I take a set of text (65,000 characters), and paste it into the text
control. all looks well. Then when I click a button I print out the
entered text and the length of that text. Here is what I am seeing...

1. Paste in text (65,000 characters)
2. Click button
3. Output on screen shows that the message length (i.e. len(msg)) is
30003 (strange since it should be 65000)
4. Select all text in the text control and hit delete. The text
control should now be empty.
5. Paste in text (65,000 characters)
6. Click Button
7. Output on screen shows that the message length (i.e. len(msg)) is
65000 (as expected).

Any idea why the first time it gives me 30003, but on subsequent
attempts I get 65000?

Thanks