As already mentioned here http://chdk.setepontos.com/index.php?topic=10361
we need an option to set the function of the DISP-button to the REC-button. This is critical for cameras (like Powershot A810, A1300, A1400…) that do not come with a dedicated DISP-button.
Otherwise users won't be able to turn of the display, since the DISP-button is the same as the down-button on these cameras. The latter is already used for exposure compensation. Plus one can't reach a super-menu quickly, which can be very annoying. Also, in the layout editor it is not possible to set the 1-pixel steps, which almost renders the editor useless.