Comment 4 for bug 1351091

Thanks for the suggestion.

Frequency of search varies widely across apps. In a browser or address book, it's fairly frequent throughout your use of the app. In a calendar or music app, it's a bit less important. In a weather app, it's probably infrequent (unless you're a globetrotter or similar). In a notes app, it's something you'll usually use when you've just started using the app after minutes/hours/days of not using it. And so on.

So we shouldn't necessarily expect a search feature (or a share feature, or a print feature...) to be accessed in exactly the same way in every app. Consistent position can be good for learnability, but it also risks making a feature invisible. (The same is true on the PC: "Find" might always be in the "Edit" menu, but outside of menus, the prominence of a search command varies widely between apps, as it should.)

The case of System Settings is similar to a notes app: search is something you're most likely to use when you're entering the app after some time not using it. Specifically, when you've decided to change a setting and you're looking for that setting. So I think it's correct for the search to be visible by default on the main screen, not even requiring a tap to get to; for it to scroll out of the way if you move down to the categories; and for it not to be present at all on secondary screens. And the first two of these mean that it can't be in the header.