On Windows 10, I have the "on top" preferences disabled. If I start up REW V5.20.9 with no input or output device selected, and click on SPL Meter, Generator, or Scope, the new window momentarily flashes up, but then the main window immediately gets brought to top. If I then click on a section of the partially obscured secondary window, it again momentarily flashes on top, but then the main window immediately gets brought to top again. Unless the main window itself is also partially obscured, in which case the secondary window correctly comes to top. But if I click on the secondary window's icon in the task bar, it always gets properly brought to top and stays there.