setBackgroundImage behaviour changed on ipad 4.2

after the update to 4.2 the setBackgroundImage behaviour changed! in my custom uibutton i have a white image as background (set with setBackgroundImage:forState:) and another image with a transparent layer (set with setImage:forState:) On iPad 3.2 and on all versions of iPhone this gets rendered as

while on an iPad with ios 4.2 it gets rendered as

http://i52.tinypic.com/530005.png

i don't know whether the background image is spreading outside its bounds (256x128) or it reduces the si开发者_JS百科ze of the above image. This happens both on device and on simulator.

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Well after a long search, I couldn't find any reason behind this.

I worked around it by loading the custom button programmatically instead of from Interface Builder.

I hope it helps.