How to display NSMenu with a search field to limit the number of results (similar to the Xcode menu)

Question

This kind of menu is available in Xcode when searching for a function name (see attached image):

Is this a standard NSMenu with a custom item?

Is this a fully customized NSWindow, with custom NSViews?

Is there an open source library that can offer such a feature?

Any tips for implementing such a menu?