When I go to Data Grids - Visual in Toad Options, click the Edit Styles button, select Classic, click Edit, and change the Header's color and/or font. This does not show in the data grid when I have Classic selected as my Active Style. It will not let me change the data grid's header color or font. This is the case for all visual styles, not just Classic.
Waiting for fix to be released in a future version of Toad for Oracle.