What information does Schema Browser Img column display?
The Img column is used to display icons representing certain objects. From the right-side of Schema Browser click on the Icon Legend icon to show a listing of icons and what they stand for, such as icons for Temporary tables or Clustered tables.
You can vote on an enhancement request that has been logged to the Toad Idea Pond so users can right-click on Img column to get the Icon Legend window.