stricter use of xlim in plot.stepfun

Have a look at par(xaxs="i"), which you can pass to the plot function
as well.

Hi everybody,
Thank you very much for your suggestion, Jim.  I did not think of that
graphical parameter "xaxs".  It would really be a workaround for my
first example.
Unfortunately, it does not solve the second situation, where I would
like to add the step function to an existing plot within a specified
region.  Internally, 'xlim' will always be expanded by 'dr'
(=diff(xlim)) units to the left and to the right.
Perhaps one could add an argument to the plot.stepfun function, with
which one can specify this 'dr' variable (see the internals of
plot.stepfun) ?

Best regards,
	Sebastian