Comment 4 for bug 1476028

Here's an old discussion on the devel mailing list from 2006 about the initial interface implementation for clippaths and masks - among the discussed topics are also auto-grouping and shared versus separate clipPath / mask definitions:
http://inkscape.13.x6.nabble.com/Clip-path-and-mask-UI-patch-need-guidance-td2796832.html

Currently, Inkscape has no interface options supporting shared clipPath (or Mask) definitions, whereas live-editing of clippaths and masks without releasing first, and optional auto-grouping as been implemented since.