If you didn't try to know that, you may not be able to know this. Removing functions and features without prior notice is a common phenomenon throughout those software companies, I guess. Therefore, some software will cease working over time.It doesnt work the same way. I contacted the developers at Moom and they said Apple closed the API with Yosemite. Their workaround is to display options below the green button.
So, yeah, if it wasnt closed, RightZoom would still work. Apple does these things purposely; LESS CHOICE. Essentially, Apple's way or the highway. But we all know Apple's way doesn't apply to everyone.
Would it be possible to request them adding removed function list? I think this is highly unlikely.