Getting the mass spectrum working

The mass spectrum is rendering nicely now.   Here’s a video which shows the state of work:  

When no ions are selected, the mass spectrum shows the spectrum for all ions in the sample.  When some ions are selected, it shows a spectrum for just the ions that are selected,  The units on the x axis are AMU, and the units on the y axis are the fraction of ions that appear in a given histogram bin, divided by the bin width.  This means the area under the curve should equal 1.

As always, let me know if you are interested in Apex.