Private Messaging Display

I hate to ask this, but is there a setting for the display size of the private messaging window? Currently there are only two lines of text visible, and it's kind of hard to read a message when you can only see two lines. Then when you use the scroll wheel on the mouse it goes too far, so you have to use the arrows on the right side. It's functional, just not ideal. I'm just wondering if there is a way to make it a little bigger so I can actually see what's going on. Or is this just normal? If so it needs to be redesigned.