Code change:
<ins> # Rustdoc in-doc settings Rustdoc's HTML output includes a settings menu, and this chapter describes what each setting in this menu does. It can be accessed by clicking on the gear button (<i class="fa fa-cog" aria-hidden="true"></i>) in the upper right. ## Changing displayed theme It is possible to change the theme. If you pick the "system preference", you will be able to see two new sub-menus: "Preferred light theme" and "Preferred dark theme". It means that if your system preference is set to "light", then rustdoc will use the theme you selected in "Preferred light theme". ## Auto-hide item contents for large items If the type definition contains more than 12 items, and this setting is enabled, it'll collapse them by default. You can see them by clicking on the `[+]` button to expand them. A good example of this setting in use can be seen in the [`Iterator`](https://doc.rust-lang.org/stable/std/iter/trait.Iterator.html) doc page: ![Collapsed long item](../images/collapsed-long-item.png) ## Auto-hide item methods' documentation If enabled, this setting will collapse all trait implementations blocks. It is convenient if you just want an overview of all the methods available. You can still see a method's documentation by expanding it. ## Auto-hide trait implementation documentation If enabled, this setting will collapse all trait implementations blocks (you can see them in the "Trait Implementations" section). It is convenient if you just want an overview of all the trait implemented on a type. You can still see a trait implementation's associated items by expanding it. Example: ![Collapsed trait implementations](../images/collapsed-trait-impls.png) ## Directly go to item in search if there is only one result If this setting is enabled, you will directly be taken to the result page if your search only returned one element. Useful if you know exactly what you're looking for and want to be taken there directly and not waste time selecting the only search result. ## Show line numbers on code examples If enabled, this setting will add line numbers to the code examples in the documentation. It provides a visual aide for the code reading. ## Disable keyboard shortcuts If this setting is enabled, the keyboard shortcuts will be disabled. It's useful in case some of these shortcuts are already used by a web extension you're using. To see the full list of the rustdoc keyboard shortcuts, you can open the help menu (the button with the question mark on the left of the setting menu button). </ins>

Related discussion:
text: Rustdoc has accumulated a handful of settings that users can toggle as they read docs, but we don't document them anywhere. It would be ideal if we had some documentation about these options in the Rustdoc Book that described their functionality better than the short descriptions shown on the settings page itself. !
I don't mind picking this up, unless you want to do this yourself! I do however have some questions!: The Rustdoc book you mean is right? Do you suggest adding a new section to this book or would you include it in an already existing section? What do you believe is not clear / elaborated enough in the short descriptions? I do not know the specific details of each switch are there any side-effects that are not in the short description?
Triage: no changes. The rustdoc book is that one, ! I am not a rustdoc maintainer these days (cc ) but I would probably make a new section. While the short description is good, I think it would make sense to show the options in slightly more detail, for example, maybe a before/after.
Bit of a late reply :) Do you have something to add to this? Otherwise I will follow what Steve said!