Redmine

Motivation

Project calendar is a convenient visualization facility for all kind of events relevant to the project.
Besides events, shown by core Redmine, there are several plugins that show additional events on the calendar.
However, per our experience, customizing the core Redmine calendar makes strong dependency on particular
Redmine version and creates unwanted collisions with other plugins that override the calendar.

Suggestion

Design and implement in the core a common plugin interface for calendarizable items, so plugins that aims
adding items to the calendar would be better isolated from the core and from each other.