Looks like the options to disable focus are gone in new update.
I can't make JD to stop stealing focus without disabling linkgrabber to be shown after adding links.

There are:
GraphicalUserInterfaceSettings: Linkgrabber Auto Tab Switch (UI)
and
GraphicalUserInterfaceSettings: Switch To Linkgrabber Tab On New Links Added (GUI)

Disabling them = no switching to linkgrabber tab after adding links in background. However, it's not stealing focus anymore.

Both options on + "(...)&steal the focus" in "User Interface" options make linkgrabber to show without stealing focus...weird.