We have renamed "Severity" to "Call type" since that fits us better. In itself a minor change but we also had a need for recurring calls (for example, weekly checks of serverlogs etc..).
In order to accomodate that in mantis, i have made some routines that enable this functionality based upon the Due date of an issue.
All changes are described in teh attached file with the exception of also showing the Due date field on the "simple" views.