I have a gridded data file (gaussian cube format, though not produced by gaussian) and the data is all less than 10^-3 in magnitude (in the units that I use).

I want to be able to draw isosurfaces at different levels varying by 10^-5, but the 'surface from grid data' dialogue doesn't let me use a granularity of less than 10^-4. (Molekel versions before 5.0 had no problem with this.)