Thanks for your suggestion Araq, but as I already told Mr mratsim, the ngtk3 files are only needed for the install process, they are never used later by the users of gintro package and they are deleted after install of gintro. I could put the nim files from ngtk3 into s subdirectory inside the new gintro package, that would avoid the exec(gitclone). But I do not see the benefit. You are right, I could try to make a real nimble package from the old ngtk3 repositories -- I would have to find a top level package name for the files then which is not so easy, maybe salewskinimgtk320 or so. But no one beside me has used the low level GTK3 3.20 modules until now, and now where the high level module begins to work, I think no one will care for the old module any more. (That does not mean that it would not make sense to use them, as they are created by c2nim, they have nearly no bugs, and using them is not that difficult, when one knows how GTK3 is generally used from C.)
My most serious problem is the need for "nimble prepair" currently. Most users will just try "nimble install" and that will fail of course. I just found an nimble issue related to the before hook, see [https://github.com/nim-lang/nimble/issues/280](https://github.com/nim-lang/nimble/issues/280). So my fear is, that a plain "nimble install" will not be able indeed. I think I have to ask dom96.
