[rt-users] How to detect a custom field change in a scrip

[lobo+rt at mental.com]

Hiya, we use custom fields and they work well so far.

Now I'd like to do something in a scrip if the content of
one of my custom fields changes, say, from "foo" to "bar".
I know how to check if the field is "bar", but I don't know
how to find out if it always has been "bar" before, or if
the user just changed it from "foo".

Is there a way to run a scrip on the condition "value of a
certain custom field changed", or should I rather let the
scrip run "On Transaction" and check the current field value
against its previous value?  How to do it?

    Ciao, Lobo