barline question

[Maurits Lamers]

Hi all,

Can anyone tell me how to construct a tweak, so that I can remove the 
barline on the bar itself, but keep it in the span between the bars. I 
have been trying (and will be for the next few hours) but simply 
removing the Bar_engraver from the staff context also seems to remove 
the span_bar_engraver. I am using lilypond 2.2.5.

thanks in advance

greetings

Maurits Lamers