This program disables the Always On Top feature in Windows so that no window is ever on top of the active window.
Click here to download a ZIP file with the executable and the necessary DLLs.
While the program is running, windows won't be able to be Always On Top, so the window on top will always be the active window. You can exit this program by right clicking on its icon in the taskbar and selecting "Exit". You can also deactivate it temporarily to temporarily allow windows to be Always On Top by right clicking on its icon in the taskbar and deselecting "Disable always on top".