To change the size of the Buff window go dow to this portion of the code.
Code:
<Screen item = "BuffWindow">
<!--<ScreenID/>-->
<Text>Effects</Text>
<RelativePosition>false</RelativePosition>
<Location>
<X>496</X>
<Y>230</Y>
</Location>
<Size>
<CX>210</CX>
<CY>325</CY>
</Size>
Change the <CX> value to change the width and modify the <CY> value to change the height.
Aslo as UniDyne said it is a problem in your definition size.