When you type something in chat, and press enter to send, chat remains open. If you press enter with no message - chat closes. Or you can use Esc button as usual.

Default value: 100.

• HH - hours in 24 format
• hh - hours in 12 format
• a - AM/PM
• mm - minutes
• ss - seconds
• SSS - milliseconds

Full documentation about format string: https://docs.oracle.com/javase/8/docs/api/java/time/format/DateTimeFormatter.html