The preview plugin currently relies on the current document having a KPart able to view the current file. This strongly limits the use of the plugin. Often we are working with non preview-able files that are compiled to a preview-able file. Examples might be a TeX documents or Lilypond scores, which are turned into .pdf files using an external program.

I think it would increase the use cases for the preview plugin significantly if we could get it to handle such cases. One thing that could be done for example is to allow specification of output files for certain Mimetype, e.g. to have a configuration telling the preview plugin that e.g. on a file file.tex it should attempt to locate file.pdf for preview. Maybe this could even include an optional call to an external program so that updating the preview automatically renders the document using the given program (although this is not particularly important, as one can already configure such actions e.g. on save).