An entire row or column. Click the row or column heading. Row heading. Column heading. You can also select cells in a row or column by selecting the first cell and then pressing CTRL+SHIFT+ARROW key (RIGHT ARROW or LEFT ARROW for rows, UP ARROW or DOWN ARROW for columns).
If you like this, you might also like hihat. It is very similar, but more focused on running and testing browser applications. Hihat uses browserify to bundle everything into a single source file, and uses watchify for incremental file changes. In some ways, devtool is a spiritual successor to hihat.
A chroot'ed environment is often called a chroot jail. It basically restricts the view of a set of processes so they think that the specified directory is the filesystem root. This should not be confused with FreeBSD's jail functionality, which is a chroot on steroids (with lots of additional functionality that provides more isolation than a simple chroot would).