title: Date/Time Picker as Property Editor in a TCollectionItem descendant
body: <p>I'm writing a component which requires properties of type Date, Time, and Date/Time. I would like these properties to be visible in the Object Inspector, with an option to use a popup property editor.</p>
  
  <p>I have tried <code>TDate</code> as a published property, and this gives me the results I need for just Date alone. However I need the same thing for <code>TTime</code> and <code>TDateTime</code> but they don't come with a property editor, and in fact it won't even accept any value I type in there either.</p>
  
  <p>I have found the <code>TDateTimeProperty</code> which can be used as a property editor, or so I understand anyway. I have done the necessary implementation when registering this component. This property I need to apply it to is actually a <code>TCollectionItem</code> descendant, not necessarily a part of the component but within it.</p>
  
  <p>This is how I'm registering it...</p>
  
  <pre><code>RegisterComponents('My Page', [TMyComponent]);
  RegisterPropertyEditor(TypeInfo(TDateTime), TMyCollectionItem, 'MyPropName', TDateTimeProperty);
  </code></pre>
  
  <p>Although this compiles, when I install it, there is no property editor on this property. I have tried using my component's class name in place of <code>TMyCollectionItem</code> but same issue.</p>
  
  <p>What am I doing wrong here to show this property editor?</p>