  We prove the following variant of Levi's Enlargement Lemma: for an arbitrary
arrangement $\mathcal{A}$ of $x$-monotone pseudosegments in the plane and a
pair of points $a,b$ with distinct $x$-coordinates and not on the same
pseudosegment, there exists a simple $x$-monotone curve with endpoints $a,b$
that intersects every curve of $\mathcal{A}$ at most once. As a consequence,
every simple monotone drawing of a graph can be extended to a simple monotone
drawing of a complete graph. We also show that extending an arrangement of
cylindrically monotone pseudosegments is not always possible; in fact, the
corresponding decision problem is NP-hard.
