Stop Slicers resetting Visualisation selections (eg on Donut, Pie etc)

It turns out that slicer selections immediately wipe out all visualisation selections. Not nice.

Clients constantly need to use a visualisation (eg Donut, Pie, custom Sunburst etc) to enable selections/filtering in combination with plain old slicers, but when the user clicks a slicer and loses their Donut selection, they go "d'oh!" and suddenly the page is full of data they didn't want included! Dropping the selection visualisation and moving back to 5+ Slicers is regressive, making the page ugly and unwieldy like it came out of the 80s.

This is embarrassingly awkward functionality and a difficult sell - it just needs a simple fix to keep other visualisation selections when changing Slicers (and if there is conflict, the slicer overrides properly, not wipes by default).