I have a two monitor setup. Often the window opening behavior seems to be quite the opposite of what I'd like.
For example: I can have a web-browser in one monitor, and I open up a terminal in the other display and xdg-open something, then the new window will open on top of my browser, instead of it being on top of the terminal.
Similarly, I have the launcher on both monitors, but if I open a new window from the launcher, it seems like it typically opens in whichever monitor has focus at the time that it loads. This is problematic if it takes time to load, because again, I could have my web-browser open already and want to open something else. If I click on the launcher in the other monitor and then go back to my browser, it will open in the browser's monitor.
I'm pretty sure I'm using unity, although I'm a bit confused because this is my output when I follow the instructions for finding out given here:
$ cat /etc/X11/default-display-manager
/usr/sbin/lightdm