I'd like to have my Leaflet popup (tooltip) such that it appears outside the bounding div of the map, rather than it being hidden once it hits the map border.
zindex() as a tile layer method.
What about for tips/popups?
This is not possible using the standard popup in Leaflet. The reason for this is that the map is located a
div element with the CSS-property set to
overflow: hidden. The Leaflet popup is another
div element within the map
div. Broken down to the HTML of your map, your question becomes equivalent to this one on SO.
You could make a clone of the leaflet-popup-pane
div and insert it somewhere outside of your map, but then you would need to make all the synchronisation manually, which is probably not what you want to get into.
A more feasible approach would probably be to place your popup information completely outside the map, something like in this jsFiddle. A click on the marker displays the popup information in the