"The Custom Contextual Links module allows you to add your own links to the contextual drop down widgets of blocks and nodes."

By using the version of Geshi found at https://github.com/easybook/geshi , Sass and Twig syntax highlighting can be added to text fields in Drupal.

The Jammer module hides particular elements from edit forms, similar to the Simplify module. This module is mentioned on the revisioning module/s project page on Drupal.org.

From the project page: "Simplify allows particular fields to be hidden from the user interface. This helps to de-clutter forms and present a more user-friendly experience to content editors..."

Here are some common settings for HTMLawed that can be used as a more lenient 'filtered html' format for trusted editors that need a simple WYSIWYG. This configuration allows images, which can be a security risk. If you don't understand the risk, then leave Drupal's defaults the way they are and perhaps try to work with the Full HTML format or use CSS classes and stylesheets.

The htmLawed module enables the use of the htmLawed(X)HTML filter/purifier with text/input formats.

This module lets you use very fine grained html filtering.

See /docs/common-htmlawed-settings for common settings.

Rabbit Hole is a module that adds the ability to control what should happen when an entity is being viewed at its own page.

Also see Internal Nodes

Here are some examples of using Drupal's states API. It shows the use of OR and XOR (which only work with jQuery 1.8 or above, apparently). More examples can be found in the examples project in the form example module.

"Panels are great, but how do I change this one page?"

In a hurry to get this information up... Sorry for any typos :)