security - How can access on an android device be restricted to applications or widgets on the home screen only?

This is a rooted Nexus 7 with 4.4.4 (factory image from Google).

I'd like to restrict access to anything that's not on one of the home screens.

Apps and widgets on one the home screens should be the only thing accessible without entering a code. Ideally, just activating the apps button that shows the full list would ask for a code. The link to the full settings page from the drop down menu by the clock should also be locked.

This does not need to offer a high level of security against experts, just a basic level of protection.

Strong preference for open source solutions, but let's see what's available in general. Maybe some kind of a launcher?

Existing kids mode solutions are not a good fit. I didn't look through all of them, but they seem to limit the number of available apps, and would not be suitable for an adult due to their interface.

Kiosk and app lock solutions: I reviewed quite a few options. Some are geared towards showing a web page only, others have odd intentional characteristics such as not starting on boot. Most, however, have a long list of permissions that have nothing to do with their functionality. This is a common problem that open source apps tend not to have, hence my preference for them.

Thanks in advance.