Comment 16 for bug 174468

Releases and milestones have subtly different behaviour; so attempting
to "hide the differences" is (I suspect) contributing to the problem
not solving it. If the _only_ cycle possible was a purely linear one:

  Create -> Milestone -> Release -----+
  Delete <- Milestone <- Unrelease <--+

then I think this would help to stop tripping up as there's less
code-paths for the user to get their head around. It would remove the
weird two-stage stacked dialogue currently presented when creating a
release.

Since a release (seems to) require a milestone, one user could simple
select their existing milestone and "(+) Release" it. This way the
two steps are /genuinely/ two steps, rather than being forced on the
user as a double-stacked dialogue.

(Chris: the issue of discoverability is separate and →bug #40497)