to improve performance on servers running Windows 2000, Microsoft gave administrators the choice of optimizing the operating system's memory and processor usage patterns for background services or for applications. Windows 2000 also introduced core system administration and management features as the Windows Installer, Windows Management Instrumentation and Event Tracing for Windows (ETW) into the operating system. Plug and Play and hardware support improvements The most notable improvement from Windows NT 4.0 is the addition of Plug and Play with full ACPI and Windows Driver Model support. Similar to Windows 9x, Windows 2000 supports automatic recognition of installed hardware, hardware resource allocation, loading of appropriate drivers, PnP APIs and device notification events. The addition of the kernel PnP Manager along with the Power Manager are two significant subsystems added in Windows 2000. Windows 2000 introduced version 3 print drivers (user mode printer drivers) based on Unidrv, which made it easier for printer manufacturers to write device drivers for printers. Generic support for 5-button mice is also included as standard and installing IntelliPoint allows reassigning the programmable buttons. Windows 98 lacked generic support. Driver Verifier was introduced to stress test and catch device driver bugs. Shell Windows 2000 introduces layered windows that allow for transparency, translucency and various transition effects like shadows, gradient fills and alpha-blended GUI elements to top-level windows. Menus support a new Fade transition effect. The Start menu in Windows 2000 introduces personalized menus, expandable special folders and the ability to launch multiple programs without closing the menu by holding down the SHIFT key. A Re-sort button forces the entire Start Menu to be sorted by name. The Taskbar introduces support for balloon notifications which can also be used by application developers. Windows 2000 Explorer introduces customizable Windows Explorer toolbars, auto-complete in Windows Explorer address bar and Run box, advanced file type association features, displaying comments in shortcuts as tooltips, extensible columns in Details view (IColumnProvider interface), icon overlays, integrated search pane in Windows Explorer, sort by name function for menus, and Places bar in common dialogs for Open and Save. Windows Explorer has been enhanced in several ways in Windows 2000. It is the first Windows NT release to include Active Desktop, first introduced as a part of Internet Explorer 4.0 (specifically Windows Desktop Update), and only pre-installed in Windows 98 by that time. It allowed users to customize the way folders look and behave by using HTML