Update: In the latest image (1.9.9aa) which has this issue corrected
in 1.9.9a image, ctrl+N or F6 does not work due to permission issues, here is a work-around to make it work.
From the USB keyboard, press ctrl+alt+t to get a terminal window, (if video is playing please issue "pkill node;sudo pkill omx" to clear the video)
Issue the following command
chmod +x -R /home/pi/piSignagePro/misc/*
Now ctrl+n should work.
Thanks to Alessandro, for reporting the bug!