gather info on how Tor Launcher uses bootstrap status messages

As part of the effort to improve the user experience during Tor Launcher bootstrap (legacy/trac#21951 (moved)), it would be helpful to know some details of how Tor Launcher currently uses bootstrap status messages (STATUS_CLIENT BOOTSTRAP asynchronous messages from the control protocol). Among other things, it could help Core Tor make short-term incremental changes to vastly improve the user experience.

• Does the progress bar currently map phase numbers directly into percent-done on the bar?
• Does it do anything with TAG= keywords in the BOOTSTRAP messages?
• Does it do anything with SUMMARY= strings other than displaying them in the dialog box?
• How does it know when to display the "copy logs" button with the warning icon?
• Which other of the BOOTSTRAP keywords does it use and how?
• Does it use any other asynchronous control protocol messages?