What happened with the possibiltiy to have multiple composition windows open at the same time? Am I just blinded by the sharp blue color or is it actually gone..?
If so please put it back asap!!
If I right click on the composition window tab you could get a "New window" option but it's not there anymore.
It's available under the View menu:
New Viewer (hotkeys: Ctrl + Alt + Shift + N)
Not sure why they took it off of the context menu on the tab, though...
I think that you're misremembering. It wasn't under the right-click context menu; it was under the menu that appears when you click the composition name itself in the panel tab. It's still there. All that has changed is that the active area for opening that menu is just the composition name, not the whole tab.