Some modules are dynamic during initialization, but once the initialize() stuff has been done, parameters are fixed.

Other modules want to be dynamic during callbacks (i.e., changes to parameter values), which makes things more challenging. In particular, such dynamic changes are not reflected in the input harvester UI currently, because the UI is only built once, and not rebuilt when callbacks occur.

It would be nice to have a more powerful UI that supported iteratively dynamic modules. And it would be nice to be able to tell the difference between these two sorts of modules in a programmatic way—e.g., if they extended different abstract base classes.

See also this thread on imagej-devel.