The property visibility is not implemented.
I would need especially the visibility="hidden" behavior for block elements.

Proposal for the fix for Block:

1. Change the definition of the visiblity property in foproperties.xml
to:
  <property>
    <name>visibility</name>
    <inherited>false</inherited>
   <!-- 
    original code:
    <datatype>ToBeImplemented</datatype>
    <default>visible</default>
    changed my martin.aubele@gmx.de
    -->
    <datatype>Enum</datatype>
    <enumeration>
      <value const="VISIBLE">visible</value>
      <value const="HIDDEN">hidden</value>
      <value const="COLLAPSE">collapse</value>
      <value const="INHERIT">inherit</value>
    </enumeration>
  </property>

2. Put the following line at the beginning of Block#layout:

Property visibility = this.properties.get("visibility");
if (visibility != null && visibility.getEnum() == Visibility.HIDDEN)
  return new Status(OK);