OSDUIHelper, a daemon that displays on-screen graphics when certain settings, such as volume or display brightness, or adjusted. PIPAgent, which manages the picture-in-picture feature available in macOS Sierra and later. Photo Library Migration Utility, which can migrate iPhoto and Aperture libraries to Photos. PowerChime, present on some MacBook models, plays a chime when the notebook is plugged in to power. ReportPanic, an app that displays a window when the system reboots from a kernel panic; it allows the user to send a report to Apple. screencaptureui, a daemon responsible for drawing the user interface shown when taking a screenshot. ScreenSaverEngine, the process that handles screen saver access. When invoked, it will display the screensaver. SystemUIServer, a daemon that manages status items in the menu bar. ThermalTrap, a daemon which notifies users when the system temperature exceeds a usable limit. Ticket Viewer, an app that displays Kerberos tickets. UnmountAssistantAgent, which displays a dialog if there is a process preventing ejection of a disk and offers to forcibly eject the disk if the process cannot be quit. Wireless Diagnostics, an app that launches when W-Fi connectivity problems are detected. Older applications Classic The Classic Environment, usually referred to as Classic, is a hardware and software abstraction layer in PowerPC versions of Mac OS X that allows most legacy applications compatible with Mac OS 9 to run on Mac OS X. The name "Classic" is also sometimes used by software vendors to refer to the application programming interface available to "classic" applications, to differentiate between programming for Mac OS X and the classic version of the Mac OS. The Classic Environment is supported on PowerPC-based Macintosh computers running versions of Mac OS X up to 10.4 "Tiger", but not with 10.5 "Leopard" or Macintoshes utilizing any other architecture than PowerPC. The Classic Environment is a descendant of Rhapsody's "Blue Box" virtualization layer, which served as a proof of concept. (Previously, Apple A/UX also offered a virtualized Mac OS environment on top of a UNIX operating system.) It uses a Mac OS 9 System Folder, and a New World ROM file to bridge the differences between the older PowerPC Macintosh platforms and the XNU kernel environment. The Classic Environment was created as a key element of Apple's strategy to replace the classic Mac OS (versions 9 and below) with Mac OS X as the standard operating system (OS) used by Macintosh computers by eliminating