TrackScheme windows fail to render graph with merging spots

[maarzt]

The TrackScheme windows fail to render a graph where two spots merge, like this:

    O
  /   \
 O     O
 |     |
 O     O
 |     |
 O     O
  \   /
    O

The BDV window renders the graph properly. But the normal TrackScheme, the Branch TrackScheme and the HierarchyTrackScheme fail to render the graph properly. Below is a screenshot that shows the problem.

Here is a small mastodon project with the diamond shaped graph:
diamond-shape.mastodon.zip

[maarzt]

It is this commit d17a80f that causes the problem.

[tinevez]

Do the nodes are painted in TrackScheme but overlap?

[maarzt]

No, it didn't seem like they where painted overlapping... It's probably more complicated, could be that a dense region of width=0 was created to represent the merging spot. Anyway, there's a fix already ;)