Here is an observation and suggestion. As we all know, the FormsAPI was a REALLY BIG change for 4.7. If I recall correctly, it was relatively late in the release cycle (last fall I think) when it was included. The fact that all forms for core and many contrib modules have to be rewritten is a huge effort. Refactoring parts of it (e.g. _execute to _submit, and many other changes) made the learning curve very steep for module developers. So, in the future, for new features that have a far reach, and scope/magnitude, such as the new theme system proposed by Adrian, and is being discussed in the themes mailing lists, I propose that they be considered only if they are relatively early in the release cycle, so we have time to squash the bugs, get over the learning curve, ..etc. Now, back to getting 4.7 out of the door ...