A simple Visual Studio extension that allows you to collapse all outlining sections in the current document except for the currently highligted one.

Adds a new menu item: Edit > Outlining > Collapse Everything Else

By default, the command is bound to the shortcut key Ctrl+M,S (e.g. Collapse 'some').

Install this extension using the .vsix from the latest release.

For more details on the implementation of the extension, see the writeup I did of the process.