Not sure if anyone else has this issue but it's driving me crazy on my MBAir 13 with an external monitor. Basically what happens is I will have Excel open with a bunch of windows open, all might be on my laptop. On my laptop I have a Chrome window, and on my external monitor I have another Chrome window.

Say I'm in Chrome on my MacBook Air display, and I press Command Tilda to switch the focus to the one on the external monitor, the focus does change, but fricken Excel and all of it's sheets pop open now in FRONT of Chrome on my Macbook Air. When I press Command Tilda to switch back, it switches to Chrome and Excel disappears.

I believe Word does this also, but it's insanely annoying when I am working on one window in Chrome and switch to another. It does this even if I click the window on my display with the mouse. It does this with every program, just tested with Safari and it does the exact same thing, Excel popping open. I literally need to minimize Excel to get rid of it, but even that still causes issues. Has anyone else experienced this or have any ideas what might cause this? Nothing is in full screen mode. Thanks!