Cubase Studio 4 Mixer doesn't move to the back

This has just recently been happening and it’s been quite annoying. When I have the mixer window open and go to add a new insert/plug-in, the plugin opens up, but it’s always behind the mixer. It won’t automatically come to the forefront, which it use to do. I didn’t change any setting to my knowledge. Is there a way I can correct this so that if I open a plugin or new window, it will come to the forefront?

Using a Mac.