title: How to hide a custom field type from new column choices
body: <p>I'm trying to figure out a clean way to hide a custom field type from the list of available columns when a user goes to add a new column to a list.  I only want this field type to show up when a given feature has been activated (the feature could be site, web, or web app scoped for my purposes).</p>
  
  <p>One theory (haven't had a chance to try implementing this yet) is that I could set all the ShowOnListAuthoringPages (and similar) properties to "false" in the fldtypes_myfield.xml file, then programmatically set this value to true when a given feature is activated.</p>