I am running Ubuntu 11.10 as a guest OS using VirtualBox 4.1.16 installed on Windows 7 Ultimate.

On my laptop I'd like to be able to run Ubuntu in full screen mode at 1600 x 900. I only have options within the virtual machine to select 4:3 display settings such as 1600 x 1200, 1440 x 1050 etc.

I have guest additions installed.

At the windows command prompt, I tried typing:

VBoxManage setextradata "Virtual Ubuntu Coursera ESSAAS" "CustomVideoMode1" "1600x900x16"

This didn't work, still no 1600 x 900 res available in Ubuntu.

I tried this having read the following section of the VirtualBox help (this also says something about a 'video mode hint feature' not sure what this means):

9.7. Advanced display configuration 9.7.1. Custom VESA resolutions Apart from the standard VESA resolutions, the VirtualBox VESA BIOS allows you to add up to 16 custom video modes which will be reported to the guest operating system. When using Windows guests with the 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 CustomVideoMode 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 be supplied to Linux:

vga = 0x200 | 0x160 vga = 864 For guest operating systems with VirtualBox Guest Additions, a custom video mode can be set using the video mode hint feature.

UPDATE 02.06.12

I've just tried creating a new virtual machine using the same original disk image I had been given. This had Guest Additions v 4.1.6 installed and provided me with the 1600 x 900 full screen display I want. It's after I then install Guest Additions v 4.1.16 (the version included with my VirtualBox installation) that my only choices are 4:3 displays e.g. 1600 x 1200. Seems this is the cause.