code: public void addActionConstraint(final WButton button, final ActionConstraint constraint) {
  		if (button.getParent() != actions) {
  			throw new IllegalArgumentException(
  					"Can only add a constraint to a button which is in this table's actions");
  		}
  
  		getOrCreateComponentModel().addActionConstraint(button, constraint);
  	}
docs: Adds a constraint to when the given action can be used.
  
  @param button the button which the constraint applies to.
  @param constraint the constraint to add.