  The linear dispersion relation for longwave surface perturbations, as derived
by Levine et al. Phys. Rev. B 75, 205312 (2007) is extended to include a smooth
surface energy anisotropy function with a variable anisotropy strength (from
weak to strong, such that sharp corners and slightly curved facets occur on the
corresponding Wulff shape). Through detailed parametric studies it is shown
that a combination of a wetting interaction and strong anisotropy, and even a
wetting interaction alone results in complicated linear stability
characteristics of strained and unstrained films. PACS: 68.55.J, Morphology of
films; 81.15.Aa, Theory and models of film growth; 81.16.Dn, Self-assembly.
