Below are two workarounds, didn't quite get there, but maybe they can give ideas.
They come from here:
Using a table as the Source, it highlights the selected field as blue
but all other selections are yellow.
Using a bar graph as the Source, it will only outline the selected choice.
Please see workbook v10.5 attached in the Forum Thread.
277825grey.twbx 107.3 KB
Apologies for not explaining.
There are a few more steps:
-click on the Color shelf and select the white color (or whatever your background)
-set the x-axis maximum to be one
-hide the x-axis header
-click on the Label shelf and set the Alignment to Left