I think this would good. Created a similar issue here:
https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1068774 However, I don't think it's common that one manually installs a package that one already had installed as a dependency and doesn't want to
mark it as manually installed, or is it? I think example scenarios would be useful.
--- SoupGate-Win32 v1.05
* Origin: fsxNet Usenet Gateway (21:1/5)