Strange. This is all I’m doing there:
bpy.types.VIEW3D_HT_header.prepend(VIEW3D_HT_KE_TT.draw)
Really basic standard stuff. If Scatter is doing something that doesn’t play nice with this, not much I can do on my end. (It is quite likely I may have missed something, we’ll see what Dorian comes up with ;> )
update: Dorian did find one mistake I had made, it has been fixed. However, Scatter will also need an update for other reasons, but I’m done on my end 
update2: Scatter5 Open Beta - #2241 by BD3D