The dynamics of tunneling two-level systems (TLSs) or other slowly relaxing objects in glasses cause a diffusional broadening of the line shapes of chromophore impurity molecules. The standard tunneling TLS model for glasses predicts that the diffusional broadening is Lorentzian. Recently non-Lorentzian absorption line profiles of chromophores were discovered in a series of glasses by means of optical hole burning spectroscopy. This paper attempts to analyze possible reasons for the non-Lorentzian line shapes. The standard model is modified to account for the dispersion of the chromophore-TLS coupling strengths, for TLS concentration inhomogeneities, and for chromophore-TLS interactions other than dipolar. It is found that in general the above modifications lead to line shapes, which are more peaked at the center and show more pronounced wings than a Lorentzian of the same width, in agreement with the experimental observations.