Firstly, it's very unclear whether the message being posted is meant to related to be tied to your own character or the entire free company.

Secondly, when you're typing one, a character limit appears in the bottom right of the window and counts down as you type each character. You're actually stopped when you reach the right margin of the text field, though, even though you still have characters remaining. Whether you run out of characters or space in the text field first is determined by the width of your characters (capital W takes a lot more space than a dot), but you should probably just make the box wider or taller.