> This I found out, yet the attachment here shows another case where it would be useful to be
> able to disable the background, namely if you have positive and negative measures in one
> plot. Somehow it suggests that CH1 and CH2 show very different values, whereas it is only a
> difference in the sign of this variables.

Ok, I added an option which lets you switch off the background. 

I also changed the background drawing such that it only goes to the y=0 axis, not the bottom of the screen. 
That should help displaying negative values.

Stefan