If you look at the default CRUD application, on the review/view screen you may have a combobox with content that doesn't display completely on one line and a little "More..." control/hyperlink/??? automatically appears at the end of the line. If you click on the "More..." it displays the full content of the combobox in a little display bubble below the combobox which disappears if you click "More..." again.
What do you have to do to activate this capability? There isn't another object anywhere in the code, so I'm assuming this is an inherent capability of the combobox control???