If you already have an 'eq2ui_ButtonStyles.xml', you can simply edit it and
insert the following text after line 2 (after the Page Name="ButtonStyles" line):

<Page Name="assist" ScrollExtent="320,240" Size="320,240">
<ButtonStyle Name="style" RStyleActivated="activated_rect" RStyleDefault="normal_rect" RStyleMouseOver="mouseover_rect"/>
<RectangleStyle Center="normal" CenterShrinkH="true" CenterShrinkV="true" Name="normal_rect"/>
<RectangleStyle Center="mouseover" CenterShrinkH="true" CenterShrinkV="true" Name="mouseover_rect"/>
<RectangleStyle Center="activated" CenterShrinkH="true" CenterShrinkV="true" Name="activated_rect"/>
<ImageStyle Name="normal">
<ImageFrame Name="image" Source="images/a_widgets01.dds" SourceRect="179,98,209,119"/>
</ImageStyle>
<ImageStyle Name="mouseover">
<ImageFrame Name="image" Source="images/a_widgets01.dds" SourceRect="179,119,209,140"/>
</ImageStyle>
<ImageStyle Name="activated">
<ImageFrame Name="image" Source="images/a_widgets01.dds" SourceRect="179,142,209,163"/>
</ImageStyle>
</Page>

Unless, if course, you already have a line beginning with Page Name="assist"
somewhere in this file (from a previous mod).

Enjoy!

www.Azilarir.com
