Whenever opening the describe window for an object, the window opens and has focus, but the Window bar does not reflect this properly and shows another window as having focus when it does not. This is just an issue when first opening the describe. After clicking onto another window and then back to the describe window, the focus will change properly, as originally expected.
This is only an issue is the window is set to display as MDI.
Enhancement request has been submitted to development for consideration in a future release of Toad for Oracle.