The gear icon is visible at: http://docs.moodle.org/en/Development:Progressive_Disclosure#Related_issues_in_the_tracker

where do you find justifications for your decisions?

The whole idea of using Gear or other symbols (also green asterisk) seems to be against your main principle - Progressive disclosure. For example http://en.wikipedia.org/wiki/Progressive_disclosure explains that

Progressive disclosure is an interaction design technique often used in human computer interaction to help maintain the focus of a user's attention by reducing clutter, confusion, and cognitive workload. This improves usability by presenting only the minimum data required for the task at hand.

and some rows later

Definition and term use
Progressive disclosure is an interaction design technique that sequences information and actions across several screens in order to reduce feelings of overwhelm for the user. By disclosing information progressively, you reveal only the essentials and help the user manage the complexity of feature-rich sites or applications. Progressive disclosure follows the typical notion of moving from "abstract to specific"; only it may mean sequencing interactions and not necessarily level of detail (information). In other words, progressive disclosure is not just about displaying abstract then specific information, but rather about 'ramping up' the user from simple to more complex actions.

In its most formal definition, progressive disclosure means "to move complex and less frequently used options out of the main user interface and into secondary screens".

If you must implement Gear think carefully the size and color of that symbol. If it is the same size as asterisk some users won't see the difference between asterisk and Gear - they are too similar if adv.gif is 8x12 px - see the attachment. If Gear is bigger than red asterisk it gets more attention than red asterisk (required fields) which causes more clutter, confusion and cognitive workload. At least if you need to use any symbols like Gear please explain the meaning clearly somewhere near button "Show advanced settings" - some people may have seen Gear in advanced settings of browsers or some programs but it is not used in forms and most people won't probably know the symbol at all. See the previous attachment.

The main point was to solve the accessibility issue: To make it possible to discern the two different symbols. I agree with you that the way progressive disclosure is used in Moodle can be an issue in itself. It has been discussed quite a bit: http://moodle.org/mod/forum/discuss.php?d=122545 http://moodle.org/mod/forum/discuss.php?d=120374

The problem to me is that this bigger issue is not trivial at all. There are lots of things to consider, and no real research seems to have been gathered anywhere of the pros and cons of different approaches. As my funding is over for this summer, I see it important to at least make the existing mechanism work so that users with deficiencies in telling colours apart can understand it.

The gear icon has its downsides. I welcome any suggestion for a better icon, but none has been found in the forum thread as I see it. It seems to me that by making the asterisk and the gear sufficiently different size and style. It does not work smaller than 14x15px though but as resolutions go up moodle icons are too small anyway.

(that image is transparent gif but tracker shows background as black...)

IE6 supports png just fine, it just can't have alpha transparency, so the png with 1bit transparency should be ok.

I have to say I agree with what Mark said in the forum thread - associating the moodle logo with "advanced item" seems like a pretty bad semantic mess.

See the comments from forum posts why 1 pixel transparent icons are not good, Olli.

And once again forgive me if you feel that I have written too personal comments or somehow have hurt your feelings - I have nothing bad to say about your excellent work. It's called critique - hopefully in positive attitude to make things better. I have tried to explain my excuses in that same post so I won't repeate them here...

http://moodle.org/mod/forum/discuss.php?d=12971

According what was agreed in the discussion, posting a patch that will accommodate for the new icon and also according to Mauno's suggestion, hilight the advanced rows when they appear. I did not think this needs to be two separate patches though strictly thinking the highlight solves a different issue than the icon and they could be two separate commits. (Note that the patch requires some CSS tweaks, namely addition of padding to the icon, also required by the icon).

Due to the fact that 1bit transparency is a requirement for Moodle icons, on very dark backgrounds the icon's edges look pretty ugly, but are still visible. The icon is the unicode character U+2691 and the font used was Sans 16pt on Ubuntu 9.04 with anti-aliasing.

The patch is not perfect and for example drop down menus (most of which are hopefully to be removed anyway) do not fit inside the highlit area, due to the rather novel ways form elements are padded vertically in the forms CSS. Someone who made that CSS for the standard theme could probably fix it. Still, it is better than nothing even now.

Unfortunately I can not be available to make any big changes to this anymore so should anyone require this to be further developed I hope they can make the changes required themselves.