[SOLVED] How to add a type to the typesUseViewActionInListings with Generic Setup?

How to add a type to the typesUseViewActionInListings with Generic Setup?

How to add a type "MyType" to the typesUseViewActionInListings property of the site_properties property in the portal_properties tool?

Using a propertiestool.xml file with GenericSetup as the following will modify the existing/default types (Image, File) to only (MyType). I need instead add MyType to the existing.

<?xml version="1.0"?>
<object name="portal_properties" meta_type="Plone Properties Tool">
  <object name="site_properties" meta_type="Plone Property Sheet">
    <property name="typesUseViewActionInListings" type="lines">
      <element value="MyType"/>
    </property>
  </object>
</object>

One could think adding all types (existing and new). This is won't suffice for us since we do not want to assume which types are already in typesUseViewActionInListings

  <element value="File"/>
  <element value="Image"/>
  <element value="MyType"/>

Solution

purge="False" does the trick!

<?xml version="1.0"?>
<object name="portal_properties" meta_type="Plone Properties Tool">
  <object name="site_properties" meta_type="Plone Property Sheet">
    <property name="typesUseViewActionInListings" type="lines" purge="False">
      <element value="MyType"/>
    </property>
  </object>
</object>