Orphaned exons in six-frame view

[mberriman]

Describe the bug

Six-frame view doesn't link together all exons when zoomed out. At some zoom levels, exons within a gene model become unconnected and therefore look like some other genomic feature. You can only see they're part of the same model when you zoom in.

To Reproduce Steps to reproduce the behavior:
Load S. mansoni,
go to SM_V10_1:34,699,293..34,830,415

Expected behavior
When zooming out, all exons should remain visually connected until the exons are no longer rendered. Even if exon reduce to a hairline, connections should be drawn.

Screenshots
At this level of zoom, an exon appears to be orphaned:

But zoomed in the exons are all correctly linked:

Version information:
JB 3.6.5
Apollo 3 0.3.8

Additional context

[haessar]

The problem was I had placed the line drawing code in a block that was gated for exons with width > 2 (alongside some of the other code that colours the interior of the boxes and draws the chevrons). I move it outside this block and it renders the connecting lines correctly.