Qmos grid broken for PosWest, Clon0 under isis3.9.1

[lwellerastro]

ISIS version(s) affected: 3.9.1

Description
The grid function does not draw properly under this version using a map having LongitudeDirection=PositiveWest and LongitudeDomain=180 (with clon=0). This is not the case under isis3.9.0, so this appears to have been introduced when changes were made by way of #3417.

See attachments below for 3.9.1 (top) vs 3.9.0 (bottom) views.

How to reproduce
Data are available under /work/users/lweller/Isis3Tests/Qmos/LonDirection/Clon0/

• Launch Qmos
• Open Cube List gll_lev1_sml.lis (data which covers all longitudes and nearly goes to both poles in latitude)
• Quick Load Map equi_PosWest180.map
• Enable Grid - broken at this point (no lines of longitude except at left end)
• Grid Options (to see if it fixes anything): Latitude increment 45, Longitude increment 60, Latitude/Longitude Range Read from map file (to get grid to extend to poles) - still broken (no lines of longitude except at left end), but clicking grid options, then apply seems to fix things. This is the attachment view.

I get similar behavior if a different map is loaded first (PosEast/PosWest clon180 - see other map files in same directory), then try and redraw with equi_PosWest180.map.

Sometimes when redrawing using a new map, the grid won't always draw properly (might be shifted by 180 degrees of longitude, one way or the other) until I click on Grid Options, then apply. That seems to draw the grid properly, though I have found I might have to hit apply a couple of times. Maybe this is a separate issue? It all seems related to me though.

Additional context
There is sort of a general problem with applying a new map file when a grid is already present. It may or may not draw the grid properly.

[Kelvinrr]

Made some progress on this today, seems like the grid logic is fine, the issue lat/lon extents are not being updated correctly when you change them (e.g. loading a different map file). I'll do some reading on signals/slots and dig through ISIS's code to see where/how the projection update needs to happen.

[Kelvinrr]

Closed by #3714