wxPython TextCtrl - weird scrolling behavior

[abcd]

I have a TextCtrl which is set to be multi-line.  I have a function
say, updateText(msg), which takes some string and appends it to the
text control...

txtControl.AppendText(msg)

....however, if the text that I am appending would cause the scroll
bars to appear/or scroll since the text is long the textcontrol appears
to be blank, until you click on the scroll bar...then the text appears.
 Any ideas?  is this is a sizer problem or a TextCtrl issue??

thanks