When I click on a .SQL file to launch Toad, the file Is loaded into a window in the editor and a new empty tab is also opened.
The reason for this is because there must be a connection associated with the editor instance. Toad has no idea what connection you want to associate a SQL file to when you double-click it or right click open, so it starts Toad and opens an editor with the SQL in the editor window. You must choose a connection from the Change Session button --either a new connection or a recent connection from the fly out. This is the same exact thing as starting Toad, making NO connection, but opening the editor. Type any SQL in the editor and it's not going to be executable until there's a connection.