I use my Canon S95 for UW photography (diving). The house I have for the camera does not allow access to the wheel on the back of the camera. I have discovered that if I hold down the PRINT key and press LEFT or RIGHT I can adjust exp comp. without using the wheel. When CHDK is active this does not work any more. It is difficult to press two keys at the same time when the camera is in the house anyway, and it would be much nicer if LEFT and RIGHT could simulate rotating the wheel when in ALT mode. I will see if I can figure out to make this work, but help is welcome 
Since I am new to CHDK it also do not know if I am the only person using CHDK for UW photography?
I have now modified CHDK so that my S95 works well for UW photography. Here are the changes I have made:
1. In ALT mode SET, LEFT and RIGHT adjust exp comp (When the camera is inside my Ikelite UW house the jog dial is not available).
2. In ALT mode UP, DOWN zoom in/out (In my Ikelite UW house the normal zoom button does not work well)
3. In ALT mode pressing the shutter takes a picture as it does in normal mode. (Since I can not adjust exp comp and zoom in/out in ALT mode I will be taking a lot of pictures in this mode
4. When SHUTTER is half pressed the display is blank for a short while. (It is not easy to feel when the shutter is half pressed with gloves on and the camera inside a UW house therefore an instant visual clue is nice.)
While I have been working on these mods I have discovered a few possible bugs:
1. The function action_push_click(long key) in action_stack.c does not work. Modifying platform_camera.h by adding the line below makes it work:
#define CAM_KEY_CLICK_DELAY 10
2. When the jog dialis turned in ALT mode, exp comp is adjusted when you exit to NORMAL mode. To reproduce: Press PRINT, turn the JOG WHEEL and press PRINT again. On my camera EXP COMP is now adjusted one down or up.
I have been working on trunk1259.
/Sam
