Use the Test Size drop down to choose the size of the browser window when VLF-ONE is executed. The sizes are those of some commonly used mobile devices.
You can add or remove devices by editing your framework's XML definition file.
This feature should not be used out of a development context.
Note: Use of this feature in a PC web browser is in no way an alternative to testing your application on a real device. You should expect a real device to exhibit different display and performance characteristics.
See Can I run my VLF-ONE application on a tablet?