Thanks mate, much appreciated.
For anyone else:
eq2ui_mainhud_groupmembers.xml
Change:
<Page BackgroundColor="#0000FF" BackgroundOpacity="0.500" Location="1,1" Name="CueP" ScrollExtent="203,24" Size="203,24" Visible="false" />
<Page BackgroundColor="#FF0000" BackgroundOpacity="0.500" Location="1,1" Name="CueH" ScrollExtent="203,24" Size="203,24" Visible="false" />
To
<Page BackgroundColor="#0000FF" BackgroundOpacity="0.800" Location="1,1" Name="CueP" ScrollExtent="203,24" Size="203,24" Visible="false" />
<Page BackgroundColor="#FF0000" BackgroundOpacity="0.800" Location="1,1" Name="CueH" ScrollExtent="203,24" Size="203,24" Visible="false" />
So there's still a little transparency for when they overlap.
Now if only EQ2 would do CSS blink
