Well, that´s sad and it´s more sad when you see Spark it´s the only knowed corporate client for XMPP, the others clients are personals. Can you my dear friend give me the actual spark pakage so i can make it a few tweaks and configurate it to my way??? i don´t know Java/Swing but i can learn it there is a 1rst time for everything, and work in the Client Control features to enance it.
A latest spark package not too complicated and ready to compile, just for make my tweaks and compile it, then in a future add that html text.
You can count with me has an active dev for Spark.