Main: eliminate the use of SysV semaphores on all host OSes other than Windows, namely Linux, Solaris and Mac OS X, with the consequence that no system reconfiguration is needed to run more than approximately 100 VMs

Main: use the XDG standard configuration folder instead of .VirtualBox on systems where it is appropriate (bug #5099)

Main: extension pack framework can now support loading HGCM modules, contributed by Jeff Westphal

VBoxManage: list more information about hard disk/DVD/floppy media, and support the --long option to show really all available details

VBoxManage: added support for optional command line parameters for the automatic Guest Additions update

VBoxManage: added support for listing active guest sessions, guest processes and/or guest files via guestcontrol list

VBoxManage: added support for closing active guest sessions via guestcontrol session close --session-id | --session-name | --all

VBoxManage: added support for terminating active guest processes via guestcontrol process kill|close|terminate --session-id | --session-name ... or guestcontrol [p[s]]kill --session-id | --session-name ...

VBoxManage: added support for watching guest sessions via guestcontrol watch

VBoxManage: added modifyvm --triplefaultreset to make the VM reset on triple fault instead of triggering a Guru Meditation (see the manual for more information)

3D support: several fixes

3D support: several fixes for Mac OS X hosts

OVF: several fixes

Extpack Installer: make it work if the file is located in a folder with special characters

Keyboard: fix for reporting key sequences like Ctrl+Alt+Del for the USB keyboard emulation

Shared Clipboard/X11: support for BMP-format images, contributed by François Revol

Mac OS X hosts: limited support for Mac OS X 10.9 (Mavericks)

Mac OS X hosts: use a launchd script instead of the deprecated StartupItem mechanism (bug #8940)

Windows hosts: don't cause massive DPC latency (only on certain hosts; still needs improving; bug #6242)

Windows hosts: consider symlinks when retrieving volume information (bug #11962)

Windows hosts: fixed an issue with USB2 devices being inaccessible when plugged into USB 3.0 ports

Windows Additions: fixed misbehavior with guest display power management (WDDM driver only; bug #11170)

Windows Additions: fixed memory leak caused by WTSQuerySessionInformation() on Windows 2000 guests (bug #12072)

Windows Additions: ability to track guest user idle times through the newly introduced event IGuestUserStateChangedEvent

Linux Additions: fixed udev detection in the init script with Linux 3.x kernels

VirtualBox 4.2.18官方下载：

面向Windows平台：支持Windows XP、Vista、Win7、Win8、Win8.1等平台，101MB

注：VirtualBox是含简体中文语言包的，不过安装的时候要特别注意，如果您登录Windows的用户名是中文名，会导致软件无法正确安装，关于这个，大家可以看下《Win7下安装VirtualBox，系统找不到指定的路径？》。