Whistle Picture
The bottom of the window has a drawing of the whistle you are
designing, It shows the approximate distances between the end and
the holes. By approximate we mean that the values have been
rounded to the nearest whole number. At times this means that
some of the values will appear not to add up! For accuracy you
should use the values displayed in the hole editor - they are displayed
to two decimal places (if appropriate). Let me know if you need
greater precision.
If you wish to examine the whistle in greater detail, then you can zoom
in (and back out again), and rotate the whistle up or down (useful if
you have holes on the back).