On Can Build Check

Syntaxes	Version
[block] can build check	1.0

Called when a player rightclicks on a block while holding a block or a placeable item. You can either cancel the event to prevent the block from being built, or uncancel it to allow it. Please note that the data value of the block to be placed is not available in this event, only its ID.

Exemples:

on block can build check:
    cancel event