It's implemented in the same manner as the traditional "panels" (how we refer to the non-Launchpad windows). It's the same code, same implementation, same development environment. Everything's integrated. When it started out (~17 years ago) it was different and new, but the work there was taken back into the main panels to replace what you think of as old 80x25 screens. All of it is now rendered using Chromium (Blink).