If you have ever attempted to run Ubuntu 14.04 in VirtualBox you might notice the fact that the resolution is stuck at 640 x 480 . Similar issues have been reported for Kubuntu 14.04 and Ubuntu Gnome 14.04 .
There are a few easy possible solutions to this problem .
A. The first solution would be to click on Dash and search for "xdiagnose".
Once the window opens , check all the boxes under "Debug" section . Hit apply and close the window. Power off the VM and then start it back up .
After starting up the virtual OS you will notice an increase in the size of the window . You can check the resolution by searching for "Displays" in Dash .
B. Another more comprehensive solution is installing "Guest Additions" .
The VirtualBox Guest Additions consist of device drivers and system applications that optimize the operating system for better performance and usability.
Run the script and install the necessary software.
Reboot the virtual OS once the "Guest Additions" have been installed .
Using the second solution will let you resize the window on the fly with the desktop snapping right into place .
"How to" video below :