Visually distinguish secondary selections in all charts

[Roly Perera]

The current UI behaviour can be a bit tricky to understand because secondary and primary selections look identical for most of the chart types (e.g. scatter plots). For example, in the stacked bar chart/scatter plot linked outputs example, if you select a bar segment then secondary scatter plot selections look like primary selections. If the user then adds to the primary selection in the scatter plot (which is now possible with our more generic design), then the distinction matters but isn’t visible.

• Remove unselected (no longer used)
• Move chart-specific UI helpers into those charts' modules
• mouseenter to set transient to neg persistent, mouseleave to set transient to persistent???
  • Then transient should always trump persistent (no, because persistent would often look unselected then!)
• Doc: visual selection states are selected, primary, persistent (no: transient/persistent orthogonal)
• Visual selections which are primary persistent and secondary transient? (ok: transient/persistent orthogonal!)
• BarChart
• LineChart
• TableView
• MatrixView
• ScatterPlot

[Roly Perera]