VirtualBox, an open source x86 virtualization project available for free has just hit version 4.2.0. The new version, a 96.6 megabyte download, features the following fixes and changes:

New Features:
- Improved Windows 8 support, in particular many 3D-related fixes.

- GUI: VM groups (bug #288).

- GUI: expert mode for wizards.

- GUI: allow to alter some settings during runtime.

- Support for up to 36 network cards, in combination with an ICH9 chipset configuration (bug #8805).

- Resource control: added support for limiting network IO bandwidth; see the manual for more information (bug #3653).

- Added possibility to start VMs during system boot on Linux, OS X and Solaris; see the manual for more information (bug #950).

- Added experimental support for Drag’n'drop from the host to Linux guests. Support for more guests and for guest-to-host is planned. (bug #81).

- Added support for parallel port passthrough on Windows hosts.

- Enhanced API for controlling the guest; please see the SDK reference and API documentation for more information.

In addition, the following items were fixed and/or added:
- Mac OS X hosts: sign application and installer to avoid warnings on Mountain Lion.

- VMM: fixed a potential host crash triggered by shutting down a VM when another VM was running (only affected 32-bit hosts and 64-bit OS X hosts, 4.1 regression, bug #9897).

- VMM: fixed a potential host crash under a high guest memory pressure (seen with Windows 8 guests).

- VMM: improved VM context switch performance for Intel CPUs using nested paging.

- VMM: added support for FlushByASID features of AMD CPUs (Bulldozer and newer).

- VMM: fixed unreal mode handling on older CPUs with VT-x (gPXE, Solaris 7/8/9; bug #9941).

- VMM: fixed MP tables fixes for I/O APIC interrupt routing relevant for ancient SMP guests (e.g. old OS/2 releases).

- VMM: support recent VIA CPUs (bug #10005).

- VMM: fixed handling of task gates if VT-x/AMD-V is disabled.

- VMM: page fusion fixes.

- GUI: network operations manager.

- GUI: allow taking screenshots of the current VM window content (bug #5561).

- GUI: allow automatically sorting of the VM list.

- GUI: allow starting of headless VMs from the GUI.

- GUI: allow reset, shutdown and power off from the Manager window.

- GUI: allow to globally limit the maximum screen resolution for guests.

- GUI: show the full medium part on hovering the list of recently used ISO images.

- GUI: do not create additional folders when a new machine has a separator character in its name (bug #6541).

- GUI: don’t crash on terminate if the settings dialog is still open (bug #9973).

- GUI: consider scaled DPI values when display fonts on Windows hosts (bug #9864).

- GUI: if a bridged network interface cannot be found, don’t refuse to start the VM but allow the user to change the setting immediately.

- Snapshots: fixed a crash when restoring an old snapshot when powering off a VM (bugs #9364, #9604, #10491).

- Clipboard: disable the clipboard by default for new VMs (see the manual for more information). It can be enabled at any time using the VM menu.

- Settings: sanitize the name of VM folders and settings file (bug #10549).

- Settings: allow to store the iSCSI initiator secret encrypted.

- NAT: improvements for the built-in TFTP server (bugs #7385, #10286).

- NAT: fixed memory leak when disabling the NAT engine (bug #10801).

- E1000: 802.1q VLAN support (bug #10429).

- Storage: implemented burning of audio CDs in passthrough mode.

- Storage: fixed audio CD passthrough for certain media players.

- Storage: implemented support for discarding unused image blocks through TRIM for SATA and IDE and UNMAP for SCSI when using VDI images.

- Storage: added support for QED images.

- Storage: added support for QCOW (full support for v1 and readonly support for v2 images).

- Storage: added readonly support for VHDX images.

- USB: don’t crash if a USB device is plugged or unplugged when saving or loading the VM state (SMP guests only).

- Solaris additions: added support for X.org Server 1.11 and 1.12.

- Solaris additions: switched to using an in-kernel mouse driver.

- Windows hosts: no need to recreate host-only adapters after a VirtualBox update.

- Windows Additions: fixed memory leak in VBoxTray (bug #10808).

VirtualBox 4.2.0 is available for free and requires an Intel-based Mac running Mac OS X 10.6 or later and an Intel-based Mac to install and run.

If you’ve tried the new version and have any feedback, please let us know.