No. You can get and set the number of unassigned ability points, but there is no event that tells you when it changes. You could check it on a timer, but that's not really nice.
Wait, there is a unassigned ability point check? What is it, and are there ones also for talent points and attributes? I know these existed for D:OS1, but I thought they were removed. If these exist, then adding new abilities, attributes, and talents is possible in a hacky way.
