The dialog is pretty straightforward. This is the first editor that
can cause a partial update -- if you edit a label, only the lines
that refer to that label are regenerated -- so I added the code for
partial display list updates as well.
Also, while working on this I noticed that long comments were getting
ellipsized at a bad place. The column width for the semi-hidden
column used for notes and long comments wasn't getting set. After
fiddling with it a bit I determined that it really needed to be set to
the sum of the widths of the rightmost four columns, and updated
whenever column sizes change. This was easier to do than I expected.
I may actually be getting the hang of WPF.
