By default, the Atom editor hides files in its sidebar that match your VCS ignore file. This can be frustrating, as a hidden file isn’t necessarily one you don’t care about – for example, the node_modules folder will typically be excluded from a Node.js application, but you may wish to jump in and examine a module, do some debugging etc.
I wanted to show hidden files, so naturally I went to Preferences to look for an appropriate setting and found one that looked just the ticket: Settings > Core Settings > Exclude VCS Ignored Paths.
I figured that unticking this setting would do the job, but it made no difference – confusingly, it turns out that this is a global setting used by functionality such as fuzzy searching, and there is another setting that overrides this for the sidebar (a.k.a. tree view). Because Atom is modular, most of its components exist as independent packages. The setting you need is found in Settings > Packages > Core Packages > Tree View:
Here you’ll find “Hide Ignored Names” and “Hide VCS Ignored Files” settings – the latter is the one you want to stop the sidebar from ignoring files that your VCS ignores.
The first setting relates to another of the settings back on the main Settings panel (see first screenshot above) – Preferences > Settings > Core Settings > Ignored Names. This allows you to globally ignore file/folder patterns regardless of VCS ignore files. You probably want to leave this on unless you really want to be able to dig around in your `.git` folder within the editor.