expects: decimal between 0 and 100
    returns: alpha value for rgba

def decimal_to_alpha(dec):
    """
    expects: decimal between 0 and 100
    returns: alpha value for rgba
    """
    dec /= 100.0
    alpha =  hex(int(dec*65535))[2:]
    while len(alpha) < 4:
        alpha = '0' + alpha
    return alpha