Redmine

At [Planio](https://plan.io/redmine-hosting) we've had users of the Chrome browser reporting that sometimes, the tooltip of links was placed in a way that made it turn on and off while the mouse was placed over the link. It's a bit hard to reproduce but often happened with narrow viewports and long tooltip content on the edge of the window that got wrapped around onto a second line of text in the tooltip.

The attached patch fixes that by making the tooltip itself non-reactive to pointer events.