Let GenIdea take a query of targets you wish to generate for

[lihaoyi]

e.g.

mill mill.scalalib.GenIdea/idea __[2.12.7] # Generate projects for 2.12 cross build
mill mill.scalalib.GenIdea/idea __[2.11.12] # Generate projects for 2.11 cross build
mill mill.scalalib.GenIdea/idea __[2.11.12].js  # Generate projects for 2.11 JS cross builds only

This would basically be a more flexible version of @lefou's #458, letting you on-the-fly select what versions of your cross modules you wish to generate Intellij projects for rather than needing to specify it up front in the build file