Mouse drag: add a new curve.
Space: Turn on / off the clock.
s: Proceed one time step.
r: Reset.
m: Switch flow to mean curvature flow / volume preserving mean curvature flow.
h: Switch flow to heyperbolic mean curvature flow / volume preserving hyperbolic mean curvature flow (which in fact describes the dynamics of a soap bubble).
t: Show tangents and normals.