Shoutbox

Since I think those are just SetWindowText, and GetWindowText, they are limited like that.

And:
[ b ]Testing[ /b ] shouldn't be bold if MessengerPlus!'s hook attaches to the richedit, which I don't know. If you want to know the "bold code" in RTF (Rich Text Format) , open Word (or WordPad which is included in Windows), type a bold word, and save it as RTF, then open it in Notepad.