windows版和linux版跳过4.2.1，直接发布了4.2.2；

This is a maintenance release. The following items were fixed and/or added:

• VMM: adapted to changes in Mac OS X 10.8.2 (bug #10965)
• GUI: restored VM item tool-tip functionality (4.2 regression)
• GUI: added group item tool-tip functionality
• GUI: fixed handling of the .ova/.ovf file name association (4.2 regression)
• GUI: it was not possible to change any setting before the first VM was created (bug #10928)
• GUI: disable grouping action if all the selected items are full children list of the same group already
• GUI: added menu for runtime drag-and-drop option change
• GUI: cleanup shared-clipboard menu on visual-mode change
• GUI: make sure VM receives keyboard focus on entering fullscreen-mode on Win host (bug #11051)
• GUI: disable proxy authentication for security reasons
• 3D Support: DrawIndexedPrimitiveUP implementation fixes for the Windows WDDM video driver (bug #10929)
• Storage: fixed a release assertion in the AHCI emulation when requests where canceled with asynchronous I/O disabled
• Storage: fixed a hang during VM reset under certain circumstances (bug #10898)
• NAT: fixed a crash under rare circumstances (Windows hosts only; bug #10128)
• NAT: automatically use the host resolver if the host name server is set to some unusual loopback value (bug #10864)
• E1000: fixed a VirtualBox crash during intensive network transfers (4.2 regression; bugs #10936, #10969, #10980)
• ICH9: fixed PCI bridge initialization
• USB mouse: ensure that the last mouse event doesn't get lost if no URBs are available
• BIOS: certain legacy guests (e.g. Windows 95) didn't find the boot device after a warm reboot
• BIOS: don't trash the palette in text modes when setting the border color
• EFI: fixed OS X guest autoboot (4.2 regression)
• VBoxManage: fixed output of showvminfo --machinereadable (bug #10973)
• VBoxManage: fixed parsing of storageattach --discard (bug #11023)
• VBoxManage: fixed wrong output of the HPET setting in showvminfo (bug #11065)
• VBoxManage: fixed closing the guest session after executing a guest process via guest control
• VBoxShell: adaptions to interface name changes
• Guest Additions device: fixed a Guest Additions hang when a machine was reset after a crash
• Linux hosts / guests: Linux 3.7-rc1 fixes
• Linux Additions: support X.Org Server 1.13
• Linux Additions: fixed a hang when the X server was restarted with old guest kernels
• Linux Additions: fixed a VBoxService crash during CPU hot remove (bug #10964)
• Windows Additions: fixed automatic screen resize issue for NT4 guests
• OS/2 Additions: fixed shutdown hang
• OS/2 Additions: fixed mouse driver panic
• Solaris hosts: fixed autostart service going into maintenance mode after all VMs started
• Solaris hosts: fixed linking the host driver with the dtrace module

详细请看：

https://www.virtualbox.org/wiki/Changelog