Re-using Lively UI items

What would you like to achieve?
I'd like a set of high-level UI items and widgets I can use in my projects, and I know that they are already available in Lively. These include (but aren't limited to):

1. Drop-down menus
2. Menu bar
3. File browser
4. Search box attached to 1-3

The thing is, I know this stuff is already in Lively. For example, the Module Browser is amazing. But these components aren't really available to Lively developers for items other than Lively development.

How are you trying to achieve that
ATM, rolling my own (badly) by looking at the code and guessing.

Additional Resources
I think 80% of this is documentation and the remainder are a (few) very high-level methods. For example:

1. Setting the action of a button should be a single method call -- it's actually pretty much there for buttons, since there's an action field already
2. Same thing for a drop-down list: it should be a single call (addItem(label, action))

Most of this is really easy (or should be) but it's not done and a user/developer really doesn't have the information to do it themselves

Version: Please paste the lively.next commit on which the problem occurred here (use the copy button of the Version Checker in the bottom left corner).
af0c3623fbe24a48097cb69eace75feafddf0406

The issue names the Module Browser, buttons, and drop-down lists but does not identify files or tests. Start by locating those existing UI components and documenting how developers can reuse them; done should include clear usage guidance and, if needed, agreed high-level methods such as button actions and drop-down item actions.