[R] lattice/ylim: how to fix ylim[1], but have ylim[2] dynamically calculated?

[Johannes Graumann]

Hello,

When drawing "barcharts", I find it not helpful if ylim[1] != 0 - bars for a 
quantity of 0, that do not show a length of 0 are quite non-intuitive.

I have tried to study
	> library(lattice)
	> panel.barchart
but am unable to figure out where ylim is taken care of and how one might 
fix ylim[1] to 0 for barcharts ...

Can anyone point out how to tackle this?

Thanks, Joh