hi,
i just upgraded from pytho2.2 and wxPython 2.4 to:
python 2.3
wxPython 2.5.1
i use this on Windows XP Home Edition
The problem i ran into is that using transparent bitmaps as menu items no longer works. by no longer works i mean that the highlight bar no longer gets filled into the transaprent portion of the bitmap and in fact seems to add some sort of margin of 3 or 4 pixels around the image. the transparent portion shows up white and the margin white. the highlight begins immediately after this margin, flush against the left edge of the first letter.
the previous version of my program that i was running showed (and still shows) the highlight correctly.
also, this is related, i noticed that the width of the menu is calculated differently in this version. the previous one resized the menu width when there was an imagine on the menu by simply adding the width of the image to the caculated size and resizing the menu to this new width. the new version seems to disregard the additional image width so the menus look a bit cramped. it seems like the original width is left and no longer re-calculated.
just to see if it was something i did i checked on the demo for 2.5.1 and sure enough the smiley face with transparent background exhibits the same behaviour as my program 
if this has been brought up before, i apologize, but i could find nothing while searchin the archives.
thank you
/r