You're going to have to look into the internal coding:
GUI~Editor: Filter -> Show Element Library
I believe the 'verbALL' uses the 'multiple' Scripting, but I've no idea where to find it in the internal coding (presumably under the coding for Commands, but maybe not):
http://docs.textadventures.co.uk/quest/ ... mmand.html (scroll down to the 'multiple' Attribute~Script~Function category)
http://docs.textadventures.co.uk/quest/ ... /verb.html (Verb)
(wait for Jay or the other code pros: other site mods or users)
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actually, maybe you can just set the 'unresolved' Attribute for the Command~Verb (see the link above).