Allow background images to show tooltip on mouse hover.
(Background images are added to a worksheet using dummy 'X-Y' coordinates as opposed to dashboard image objects)
Currently several workarounds are possible (but with its demerits)
a) Customized shapes can mimic an image & provide tooltips but (Demerit: image resolution is poor)
related idea: https://community.tableau.com/ideas/4534
b) Images added on a dashboard can be high resolution, but (Demerit: cant provide tooltip)
related idea: https://community.tableau.com/ideas/1074
c) Tooltip may appear besides a background image if the map type is for ex: bar, circle, shape etc. but (Demerit: disoriented & not-elegant)