I am using Mac OS X 10.6.8, wxPython 2.9.3.1 and 64 Bit Python v2.7.2:
My problem is not that easy to describe in a few key words, thats why I probably did not find a solution yet. 
I just just create a very simple wx.frame with some objects and arrange them with a sizer. If I then 
show the frame all elements are displayed at top of each other for a second. Then everything jumps into place and is displayed correctly.
I tried to call all kinds of funktions before showing my frame like Refresh, wx.Yield, Update etc. but nothing helped.
Is there some function to prevent a frame to be shown before it is drawn correctly or to draw it but to not show it yet?
Thank you!
Typically when I see that issue, all that is needed is to call Layout right before you call the frame's Show() method. I would call Layout on the top sizer or the frame object. If that doesn't work, post a small runnable example and I'll update my answer.
wx Python frame elements not displayed correctly right after show using sizers