I have Word 2011 installed on my Mac.
Anyway, I have 2 monitors on my MacPro. I create a new Window ( Window->New Window ) to view my Table of Contents on the secondary monitor. When I switch to another app, like Google Chrome, then click on that new window in the secondary monitor, the window immediately moves to the primary monitor and reduces it’s width to about 10% of the monitor width.
Joy. Reproducible bug.