Pointers? Has anyone got a workaround (please don’t say “don’t use PNGs” 
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Basically … the alpha channel is not being honoured on OS X on java 1.5.x (10.4.x, latest upgrades), but is fine on windows etc.
EDIT: tester mistake - they’ve got 1.5 installed, but OS X defaults to using 1.4 unless/until you explicitly tell it to :). Its fixed in 1.5.