Hello,
A floating legend would help preserve space on a dashboard and specific visualizations. The legend is often necessary, but takes up valuable space on the visualization when it could be included in the "whitespace" of a visualization or could be a popout (similar to the way that the filter panel can be re-arranged across the page. The same legend could be used for multiple visualizations that would otherwise require individual legends which again would take up space.
Today we only have left and right place for legend, it will also usefull if we can also have top and bottom.