Version: broker-7.2.0-CR3
Preconditions:

• Login to web console
• Create any address and a queue
• Open created queue

Steps:

• Open "Send message" page ("Payload format" is json in my case (depends on previous send message))
• Choose "Payload format": xml
• Try to type xml code

Expected result:

• Tags highlighted green and tags automatically closed

Actual result:

• Highlighted rules applies from previous send message. For example, if you send json message, then reload page and choose xml then xml will be highlighted as json and closing tags will not work