Sun Microsystems VIRTUALBOX VERSION 3.1.0_BETA2 - Manual (Page 143)

9 Advanced topics
9.7 Multiple monitors for the guest
VirtualBox allows the guest to use multiple virtual monitors. Up to sixty-four virtual
monitors are supported.
Note:
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 7.4.7 , VRDP mul-
tiple connections , page 105 ) 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, VBox-
Headless 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.
9.8 Releasing modifiers with VBoxSDL on Linux
When switching from a X virtual terminal (VT) to another VT using Ctrl-Alt-Fx while
the VBoxSDL window has the input focus, the guest will receive Ctrl and Alt keypress
events without receiving the corresponding key release events. This is an architectural
limitation of Linux. In order to reset the modifier keys, it is possible to send SIGUSR1
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