"In Notebook or any program you like create a file called Capture. This file MUST be totally blank (no data of any kind in it) and be saved as Capture with no file extension.
Once you have the file created, attach your 930 to a PC and open the TomTom main directory in Windows Explorer. Create a directory called SCREEN and place the Capture file in it.
Reboot the 930. Now whenever you press the top left corner of the screen that screen will be saved as a BMP file in the SCREEN directory."
Also note that by default, windows tries to attach .txt file extension, at least in Vista. You may have to remove the extension manually. The feature remains active as long as the folder "screen" remains in place. Easy remove is changing the folder name to something like Screen2 or ScreenOff, to disable it, since you lose your "zoom out" button on the map screen.
For those having problems with the file extension I made a turnkey kit for the FRA Forums, just unzip and put the screen directory at the root of your device.
Also make sure you convert from the .bmp format to .png to significantly compress the file with no loss of quality, here is a free tool to that if need be : http://www.lunapic.com/editor/