Allow parameters of saved filters to be edited on recall

The user-configurable filters are very useful but they would be even more useful if you could edit the parameters when you recall a saved one. For example you may wish to filter on a particular date which may be different each time. At present you have to rebuild the filter every time. If the filter were displayed in the same way on recall as it was when it was created the user could change the date (or whatever) very simply.