Adding custom attachment link handler?

[arw]

It appears in older versions of zimbra it was possible to add custom handlers for attachment links in messages ...

Is this still possible? For example the Alfesco zimlet achieved this by (in zimlet init()):
this._msgController._listView[ZmId.VIEW_MSG].addAttachmentLinkHandler(...)

This doesn't appear to work in ZCS 6 however. Was this functionality moved somewhere else or is it just gone?

Thx!