I know they are supported, but I'd like to know if the "Web" designer (part of Guvnor ?) can represent/render a custom editor for them.
It doesn't seem straightforward, but at first glance it seems to do the trick, so thanks a lot!
We are adding support for custom editors for workitem handlers. This is/was possible to do with the ruleflow eclipse editor also.
Currently what's possible is to add custom editors for specific properties which is described in that link shown.