so, your pic is like 28x28? and your setting the h,w to 32x32 to get a background white border to show through?
doesn't the constructor just stretch the pic to fit the actual parameters set (ie 32x32)? thus hiding your white border?
if this is the case (and i am not sure it is), could you use 2 symbols? one larger (and under) the other? with the pic on top of the other symbol?