Many software suites allow the option to zoom in on both y and x axes on their graphs. However, ICM only allows zooming on the x-axis which often takes away the ability to see trends for lower or higher conditions. I am aware that it is possible to change the y-axis range in properties, but that is not desired since it requires changing the range numerous times as you pan through the data. This is a major caveat which sometimes changes our choice of modeling software, especially for systems which require heavy calibration and data visualization.
@Andy considering that loading the graph takes some time and it's not like excel that you can change the axis limits on the fly, this idea tries to make a way to look at the results in a meaningful way. Without the auto update you won't be able to view the results in different periods with different range, e.g. wet weather and dry weather periods. PCSWMM does it best.
The previous contributor has touched on the the strange way of configuring the 'y' axis, i.e. having to choose how many ticks for major and minor is not intuitive. It is engineering software so it would be so much better to be able to set axis values in the units which are being displayed. MS Excel does it better: Max, Min, Major units, Minor units.
I would not be in favour of the 'y' axis being auto-set based on what is being displayed in the window. Some software does this which results in (e.g.) a 1mm change in level setting the axis to (say) 0-2mm and than, when panning to another time period, the axis is changed to 0-900mm to accommodate and 850mm change in level. Again Excel does it better - Min and Max are set on the whole dataset.
Y-axis gets sub-divided onto non-standard numbers. For example, a chart with 300, 305, 310 metres in y-axis is good. But 301.3, 306.3, 311.3 metres is un-professional and less useful. By default, these values should be meaningful without having users to adjust manually each time one displays chart.