It appears that the Code Tester application is “hidden” if you open the help file (by pressing F1). Once the help file is launched, I can no longer switch to Code Tester using Alt+Tab. Code Tester is visible in the Windows Taskbar, but clicking the icon only opens the help window again. If I minimize the help window I can access Code Tester again. This isn’t exactly standard behaviour for Windows programs.
Not a big deal, but somewhat annoying if you open the helpfile to read about a certain topic and cannot get back directly to Code Tester.