The \fill-line command

The \fill-line command aligns and justifies markup text by setting as many columns as required, in a given space.

In this snippet we use numbers to (beautifully) show how the command works; but when using text beware to use quotes if you want your words to stay together:

\fill-line {The quick brown fox}
results in something like:

The quick brown fox

\fill-line {"The quick brown fox"}
results in something like:

The quick brown fox