Clickable legend group title

[nicolaskruchten]

Originally posted by @rithwikjc in #5260 (comment)

I'd like to request that the additional functionality of the legendgrouptitle having the clickable behavior of toggling the whole group, be added along with this feature introduction.

[Braintelligence]

Quick question: Is it possible to simultaneously define legendgroupclick with toggleitem but be able to click the legend group title to hide the group? Did you implement a new event handler for legend group titles or do we have to use .on("plotly_legendclick", to find out if someone clicked a legend group title?

[endursa]

Is the idea of having single trace toggle within a group still persued? or was this forgotten after the group legend toggle was implemented?