I had no luck putting pic's in the suggested user folder, but placing my own pic's in the DK L specific folder does work - sometimes
I'm unsure what the behaviour is supposed to be, but I do like the "last screen displayed" feature. It's very useful if for example you need to think about a schematic or follow a routing diagram, without having to keep pressing the on/off switch, which could be awkward if you're perched high up on a ladder
It really needs a selectable settings option. At the moment my K3's switching to the late Steve Jobs' photograph.....
If you have "FBreader" installed, you can switch to that quickly from DK L via Launchpad.