In a Sharepoint 2010 doc library, we would like to allow users the convenience of being able to enter large amounts of doc-specific text via the document Info 'data entry' panel, but NOT show all that text in the doc lib view...just show a "view details" link , so that IF a user wants to read a particular document's doc-specific text, he can click on the link and have the text pop up. Is there a practical way to achieve this? (Advice greatly appreciated!)
You should go for a custom field which inherits from SPFieldText. Nothing special should be changed in control class or field class. just change the field definition xml. Check for the tag
<RenderPattern Name="DisplayPattern"> element in field definition xml. There is this reference in msdn, but you can google for more. Also you can take a look at 14\TEMPLATE\XML\FLDTYPES.XML for SharePoint built-in fields to get some clue about field definition xml and more specifically, RenderPatterns.
You can create a simple html
<a> or even