If I launch any sub-window (i.e. Filter, Save As) from the Describe Objects window, it gets pushed into the back if you click another application you have opened in Windows and click back to Toad.
See screen shot SOL69039.jpg
This becomes a pain when I have the Describe Objects window maximized in which case once you click back to Toad, the sub-window gets hidden in the background. This in turn locks the Describe Object window as it is no longer the active window and you can get to the sub-window.
WORKAROUND: Do not maximize the Describe Objects window and you'll still be able to get to the sub-window that gets stuck in the back.
STATUS: Waiting for fix in a future release of Toad for Oracle.