I am sorry for the confusion perhaps a picture would better explain using this example on this chat see how much wider the width is where it says your message is around 2 inch's compared to mircs quarter inch, See I like to be able to see what I am typing especially if Iam trying in a large amount
http://www.techmixer.com/jquery-php-chat-free-live-chat-script/what would be nice is to have a option to resize by drag and stretch.
You should do what Collective said above. mIRC Options (Alt+O) -> Display -> Options -> Editbox lines: Automatic.
The 'automatic' setting will make the editbox widen when the text is too large to fit on one line.
ok I tried to do that it was already set to automatic when I changed it to 10 all that did was make the tool bar at top wider, when I set it back to automatic and tried typing a long message the text box (where you type the message) did not get wider it just when passed the point where I could not see it.