This appears to be limited to showing the values used as dimensions or expression. I believe it would be much more useful if we could independently define which parameters to display. Can this be made to include other parameters associated with the data points ? I'd like to use this as a possible alternative to text overlay on the data points in a scatterplot and/or boxplot.
This method below from Editing Tooltip Q worked OK for a Scatterplot (only using Add Calculated DImension) but not for a Boxplot. Perhaps that helps know if a solution is possible ?
Add the date as an additional expression. In the Display Options for this expression, uncheck "Symbol" and "Line". Check "Text as Popup".