With my 880, I can be in any activity, select a device (such as the X10 controller) and spend as much time there as I want. When I want to return to my still-active activity I press the activity button TWICE.

In my X10 (IR543) device mapped the lights 1 through 10 to the number buttons (0 being 10), then 11 through 16 to the transport keys not including REC or STOP. I put ON and OFF on the UP and DOWN buttons, DIM and BRIGHT on the volume+ and volume- buttons. For specific room lights that I want to name, I add them to the LCD display buttons. You've got room for 8 on a page, so it takes only two pages to list 16 named module numbers, in any order you want them.

I have X10 lights AND X10 cameras so I made two devices. In my Cameras device use the same IR543, but only device codes 12 through 16. Cameras obviously don't dim, so the only mapping I did in that device was to the LCD screen and the UP/DOWN buttons. My cameras are named on the screen so all I have to do is pick one then hit the UP button to have it's video signal appear in the PIP window of my TV. PIP buttons from the TV were also "learned" to the camera device so I could control the PIP position and size while in that device.