Turns out ixus300 and sx210 both have a "touch" feature on the control dial. If you touch, it's supposed to show the icon of the action that clicking on that part of the dial would trigger.
See
https://chdk.setepontos.com/index.php?topic=12245.msg121374#msg121374 In the following post, srsa_4c previously noted scripted clicks didn't work on cameras with the similar "touch control dial" feature.
From searching the PDF manuals (for "If you touch the control dial in"), cameras like sx210 are
ixus110, ixus300, ixus1000, sx210, sx220, sx230
These cameras apparently expose the "touch" as a bit in physw_status. Some kbd.c have KEY_*_SOFT keys defined for them (ixus1000 and sx230, commented in ixus100, sx210, sx220). It seems likely that setting both bits for scripted presses or clicks may be required. I'll try to come up with a test build, but it may be complicated to support in the current CHDK keyboard code.
edit:
OTOH, this probably should affect menu
Some older cameras, like the ixus65 srsa_4c mentioned have what canon called a "touch control dial" (also sometimes called feather in the firmware and CHDK) which is similar but also kind of works like a touch based jogdial. The following have this feature based on the manual
ixus65_sd630, ixus75_sd750, ixus950_sd850, ixus860_sd870, ixus900_sd900, ixus960_sd950
// Edit: G16 would also run with ...
Edit2: Ajeh, ... for the price of "AF frame select" in rec modes, so it´s probably not useful.
Code:
Sorry, I have no idea what this is about.