I’ve turn on this option at Toolbar|Customize|Options|Other but there is no shortcut hint for me on mouse over.
I’ve found a request about this issue at Ideapond (http://www.toadworld.com/products/toad-for-oracle/i/other/400696b4-95f5-4432-b7b9-b13db809ae69.aspx) and it still displays as an active idea. Do you plan to bring back this feature?