Dragging not working in new windows

[BurningTreeC]

If I open a Muuri Grid in a new window through window.open() I'm able to get the layout right, but the dragging of items doesn't work.

I assume that internally the event listeners should be attached to the new window instance or something like this Passing the window object to the Grid constructor would be an option

[niklasramo]

@BurningTreeC Interesting, would you mind sharing a reduced test case demonstrating this issue?