Multiple displays in virtual box

Feb 22, 2010
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Your Mac's Specs
21.5", 3.06 GHz intel Core 2 duo, ATI Radeon HD 4670 graphics with 256MB
I'm running virtual box with windows 7. I tried to follow the instructions from the users manual to be able to extend seamless mode onto my second monitor. I don't understand how to use the vmheadless part. I activated the multiple displays, and when I run windows it recognizes that there are two displays when i'm in the setup menu, but it still doesn't seem to recognize the second monitor. Does anybody have any experience with this?

9.4.2 Multiple monitors for the guest
VirtualBox allows the guest to use multiple virtual monitors. Up to sixty-four virtual
monitors are supported.
9 Advanced topics

1. Multiple monitors currently work only with Windows XP guests, and
Guest Additions must be installed, as the implementation resides in the
Guest Additions video driver.
2. Multiple monitors work only with the VBoxHeadless frontend. You must
also enable VRDP multiconnection mode (see chapter 7.1.7, VRDP multiple
connections, page 106) to access two or more VM displays when
the guest is using multiple monitors.
3. The guest video RAM size should be increased when multiple monitors
are used. The VRAM is shared among the virtual monitors so that only
part of it is available for each one. Therefore the available resolutions
and color depths will be reduced if the VRAM size remains the same and
multiple monitors are enabled.

The following command enables three virtual monitors for the VM:

VBoxManage modifyvm VMNAME --monitorcount 3

The following command enables VRDP multiconnection mode for the VM:

VBoxManage modifyvm VMNAME --vrdpmulticon on

The RDP client can select the virtual monitor number to connect to using the domain
logon parameter. If the parameter ends with @ followed by a number, VBoxHeadless
interprets this number as the screen index. The primary guest screen is selected with
@1, the first secondary screen is @2, etc.

The MS RDP6 client does not let you specify a separate domain name. Instead,
use domain\username in the Username: field – for example, @2\name. name must be
supplied, and must be the name used to log in if the VRDP server is set up to require
credentials. If it is not, you may use any text as the username.

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