Normally you don't need to worry about this option. The default setting ("let Mojo choose") usually works fine.
In rare cases, some people may notice odd behavior on their computers when Mojo brings a window to the foreground. This happens because Mojo generates a keystroke when it performs this action. The programs on your computer normally ignore the keystroke because Mojo uses a Japanese keyboard control character which English-language programs are not designed to detect, but occasionally a program sees the character and reacts. If this happens on your computer, select "I'll choose from the following list " and try various VK's until you find one that works.
VK means "virtual key." VK codes are numbers used by the operating system to identify keystrokes.
This page was last modified on December 7, 2013.