[8FS_Bulau]

...I know there is a little arrow that appears at the bottom, but when i click on it, it does not let me expand the window. Instead it just dissapears...

It's left-click and drag. It looks like you are clicking a little too far down.

Maybe you will have to hack it...open conf.ini in notepad, look for:

[chat]
region=(dx=1.0,dy=0.120,x=0.0,y=0.0)

This is line from mine...I have 3 lines of chat showing for 1280x1024 res.
Play around with dy value and see if it works.