Oh...( Really? No any hacky way to do this? There is no public filters etc. on block save\update? Seriously? Need this a lot. Also MetaBox is positioning itself as a great framework-like tool for programmers, not a wysiwyg-like solution for no-code experience. And I (I think, I'm not alone in this thought) expect to have all the necessary filters\hooks for my development with this solution. Otherwise, one day, unfortunately, I will have to stop using the MetaBox and switch to using native block-building practicies or some advanced solutions. Because things like this is really important.