'Number of Levels' in a 'contour legend' can be altered right on the screen and without going into the chart>edit definition. See the image below.
Yes, you can also use the mouse-wheel to skip through the # of levels quickly, and use the arrows to fine tune the number.
It will be nice if we have somehow an indication of the lower and the upper limit of the value in the plane (surface) that is being plotted, For example the range can be limited by those values while by click on the legend we can drag up or down within the absolute max/min values,
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