Register.xml

<?xml version="1.0" encoding="UTF-8"?>
<ae:configurations
	xmlns="http://agavi.org/agavi/config/parts/validators/1.0"
	xmlns:ae="http://agavi.org/agavi/config/global/envelope/1.0"
	parent="%core.module_dir%/CoveringNotes/config/validators.xml"
>
	<ae:configuration>

		<validators method="write">
			<validator class="string" provides="normal_login_set" required="false">
				<arguments>
					<argument>myNormalButton</argument>
				</arguments>
			</validator>
			
			<validator class="string" depends="normal_login_set">
				<arguments>
					<argument>username</argument>
				</arguments>
			</validator>
		</validators>

	</ae:configuration>
</ae:configurations>