No track menu options when changing alignments display to LinearPileupDisplay

[cmdcolin]

Screenshot showing this

[cmdcolin]

Just for brainstorming purposes, one option is to investigate this and fix it, probably worthwhile anyways

Another option is actually to make a PileupTrack specialized track type, separate from AlignmentsTrack, and then LinearPileupDisplay would be registered to that instead of being selectable in the "Display types" section (similar for LinearSNPCoverageDisplay)

[cmdcolin]

Note: v1.0.3 did not experience this bug from what I can tell

Also note: refreshing the page restores them

[cmdcolin]

Git bisect says 0b263b9 may have introduced the issue

[cmdcolin]

In some ways this is running into the limitations of https://mobx-state-tree.js.org/tips/inheritance

We also lost the ability to set max score on SNPCoverage track, which was a nice benefit of SNPCoverageDisplay being derived from wiggle, but was lost when we defined a composedTrackMenuItems method on SNPCoverageDisplay, because that overrode the one from LinearWiggleDisplay

[cmdcolin]

Is this related to code using displays[0] hardcoded? There are quite a number of places in the code that does this now, and may need to be reigned in

[cmdcolin]

this was fixed I believe by the change to #2226

makes sense in a way :) the old "get trackMenuItems()" may not have accurately caught what was happening, which the new "trackMenuItems()" works