I am just about finished creating custom columns through the WordPress admin panel.
The custom post type I am using is called "slides". I figured out how to add the column titles and all of the column content (because they're WordPress defaults)...what I am missing is how do I add content to the "thumbnail" column? Some kind of if statement like: if admin-thumbnail exists display the admin-thumbnail image...which sounds simple enough, I just don't know how to add it to that specific column.
The code I have so far is: http://pastebin.com/YfuYUW5c.