VirtualBox - How can I Increase Screen Resolution

As the default screen resolution option was unsatisfactory for me, I found by trial and error that the perfect resolution for a Guest on my Host's desktop (with a 19 inch LCD) is 1272 x 920. So in my HOST system, I shut down VirtualBox, then opened a terminal and typed:

VBoxManage setextradata global GUI/MaxGuestResolution 1272,920

This worked perfectly. Now when I run any guest machine in Virtualbox, the guest immediately opens to my desired screen size (1272x920) and it works consistently time after time. You can set any screen size you want this way. Absolutely no adjustments are required inside the guest machine's settings.