[Feature request]: Window offset

[szulcus]

I really like the protection so that the popover does not go out of the window.

I think it would also be a nice idea to allow an element not to go outside of a specific container. I think we have 2 potential solutions to this problem:

• prop windowOffset, which would define the safe distance from the window
• prop container, which would specify which container the popover can't go outside of
• prop containerOffset working in a similar way as windowOffset.

If you decide to support a custom container, it may be a window by default (then the first suggestion would be unnecessary).