Force a resolution on VirtualBox and CentOS

To force a certain resolution on VirtualBox and CentOS, use the following commands:

1. Create the Modeline using cvt tool:

cvt 1280 720 

Modeline "1280x720_60.00"   74.50  1280 1344 1472 1664  720 723 728 748 -hsync +vsync

2. Add it to the supported resolutions:

xrandr --addmode "1280x720_60.00"   74.50  1280 1344 1472 1664  720 723 728 748 -hsync +vsync

3. Add it to ta certain screen:

xrandr --addmode VBOX0 "1280x720_60.00"

4. Finally change the resolution using the GUI System / Preferences / Display or using:

xrandr --output VBOX0 --mode "1280x720_60.00"