@schuerle
When you set viewport manually, the viewport actually starts from the point that you provide. In some cases(Eg: column/bar) datapoints require some width in order to represent themselves on the axis.
If you want to display all the attached dataseries (in case of multi-series column/bar chart) with manual viewport, set it to half of interval (which in your case is 0.5) less/more than expected viewport value.
