Optional
The instance to edit. Without it the dialog reads data-instance-id off the anchor (a legend row's gear), and failing that edits the chart's only indicator; with several and no id it declines with a toast.
data-instance-id
Runs after every write, including a revert.
Runs once when the dialog is gone; committed is false after Cancel or Escape.
committed
The instance to edit. Without it the dialog reads
data-instance-idoff the anchor (a legend row's gear), and failing that edits the chart's only indicator; with several and no id it declines with a toast.