Windows 2000 introduced version 3 print drivers (user mode printer drivers)[64] based on Unidrv, which made it easier for printer manufacturers to write device drivers for printers.[65] Generic support for 5-button mice is also included as standard[66] and installing IntelliPoint allows reassigning the programmable buttons. Windows 98 lacked generic support.[67] Driver Verifier was introduced to stress test and catch device driver bugs.[68]