Jalview could recognise .features, .annotations and .newick files belonging to an alignment file when all dragged-and-dropped onto it

Background: improving the Getdown launcher to recognise jalviewX:// scheme URLs, use remote JVL files, open multiple files from drag-and-drop-to-icon (JAL-4409).

Wouldn't it be great if when you drag
plantfdx.fa
plantfdx.annotations
plantfdx.features
onto either an open Jalview, or a closed Jalview icon, they got associated correctly, as if they had been opened with

jalview --open plantfdx.fa --annotations plantfdx.annotations --features plantfdx.features

For the drag-and-drop onto closed icon, this could be done with a quick pre-processing of command line args in jalview.bin.Commands

Criteria for this happening, ALL initial arguments are bare arguments (i.e. there are no --arg), which is what happens when a drag-and-drop of multiple files/URLs onto the unopened icon.
Then:
for each filename with a recognised alignment extension,
  scan for the equivalent file with a .features extension. If there is one, remove it from the list and save it to add as a --features=filename.features argument.
  do same for .annotations and .newick (--annotations, --tree)

Is there a list of known tree extensions? check.