So now you have the Windows 8 Developer Preview installed as a virtual machine using VirtualBox, but you found out that the guest addition of VirtualBox doesn’t work properly in Windows 8 Developer Preview, which means that it won’t auto-adjust the resolution when you resize the window, and have to stick with the resolution available by default.
No worry. There is an alternative solution to force the desired resolution to be available in the VirtualBox guest OS, so if you have done it correctly, you can now run Windows 8 Developer Preview in VirtualBox with your screen native resolution. Instructions after the jump.
How to enable desired resolution in Guest OS
1. Close any running virtual machines and also VirtualBox
2. Run Command Prompt (cmd) as administrator (in your Host OS)
3. Manually enter the command shown below:
First, enter the below text to change the directory:
cd C:\Program Files\Oracle\VirtualBox
Then, enter the line:
VBoxManage setextradata global GUI/MaxGuestResolution any
Lastly, manually type to enter this line (don’t copy and paste, and please include the quotation mark):
VBoxManage setextradata “VM name” “CustomVideoMode1″ “WidthxHeightxDepth“
VM name have to be replaced with your virtual machine name. If your virtual machine is named Windows 8, then it should be “Windows 8″.
WidthxHeightxDepth have to be replaced with your desired resolution. Say if you want to have it running at your monitor native resolution at 1600x900x32, then it should be “1600x900x32″.
4. If you enter them correctly, your command prompt should more or less look similar to the screenshot above. Double check your spelling especially on your virtual machine name if your encounter issue. Once you done with it, you can close the command prompt.
5. Launch VirtualBox and run your Windows 8 virtual machine.
6. Once you have logged in, change the resolution via the right click menu on the desktop. You should find the resolution entered in the command prompt is available to choose.
7. After the resolution is changed, make it run in full screen by Host+F (Host is Right Ctrl by default). Enjoy!