Apart from the standard VESA resolutions, the Oracle VM VirtualBox VESA BIOS enables you to add up to 16 custom video modes which will be reported to the guest operating system. When using Windows guests with the Oracle VM VirtualBox Guest Additions, a custom graphics driver will be used instead of the fallback VESA solution so this information does not apply.

Additional video modes can be configured for each VM using the extra data facility. The extra data key is called CustomVideoModex with x being a number from 1 to 16. Please note that modes will be read from 1 until either the following number is not defined or 16 is reached. The following example adds a video mode that corresponds to the native display resolution of many notebook computers:

$ VBoxManage setextradata VM-name "CustomVideoMode1" "1400x1050x16"

The VESA mode IDs for custom video modes start at 0x160. In order to use the above defined custom video mode, the following command line has to be supplied to Linux:

vga = 0x200 | 0x160
vga = 864

For guest operating systems with Oracle VM VirtualBox Guest Additions, a custom video mode can be set using the video mode hint feature.

When guest systems with the Guest Additions installed are started using the graphical frontend, the normal Oracle VM VirtualBox application, they will not be allowed to use screen resolutions greater than the host's screen size unless the user manually resizes them by dragging the window, switching to full screen or seamless mode or sending a video mode hint using VBoxManage. This behavior is what most users will want, but if you have different needs, you can change it by issuing one of the following commands from the command line: