  Superhydrophobicity relies on the stability of drops's interfaces pinned on
sharp edges to sustain non-wetting (Cassie-Baxter) equilibrium states. Gibbs
already pointed out that equilibrium is possible as long as the pinning angle
at the edge falls between the equilibrium contact angles corresponding to the
flanks of the edge. However, the lack of stability can restrict further the
realizable equilibrium configurations. To find these limits we analyze here the
equilibrium and stability of two-dimensional drops bounded by interfaces pinned
on mathematically sharp edges. We are specifically interested on how the drop's
stability depends on its size, which is measured with the Bond number $Bo =
(\mathcal{W}_d/\ell_c)^2$, defined as the ratio of the drop's characteristic
length scale $\mathcal{W}_d$ to the capillary length $\ell_c =
\sqrt{\sigma/\rho g}$. Drops with a fixed volume become more stable as they
shrink in size. On the contrary, open drops, i.e. capable of exchanging mass
with a reservoir, are less stable as their associated Bond number decreases.
