A client upgrade from SharePoint 2007 to SharePoint 2010 surfaced the following unexpected behavior.
When clicking a icon in a list the icon lo longer links to the list item. This was the default behavior in 2007 but is missing in 2010. Since the customer still uses the 2007 user interface everything looks the same and the functionality is just missing. Very confusing for everyone.
I found the following two approaches to work around the missing functionality:
Microsoft Support: SharePoint 2010: Clicking the icon in Type column is highlighting the item instead of launching the document
CodePlex solution: DocIcon for SharePoint 2010