Mouse position tracking incorrect when track orientation is vertical

[etowahadams]

When the track orientation is vertical, the mouse position indicator is incorrect; it does not track the position of the mouse.

To reproduce:

{
  "orientation": "vertical",
  "tracks": [
    {
      "id": "1-1",
      "title": "Sample 1",
      "data": {
        "url": "https://resgen.io/api/v1/tileset_info/?d=Zz3CBDSqQ3ySrOSe2yj1eg",
        "type": "vector",
        "column": "position",
        "value": "peak",
        "binSize": 4
      },
      "mark": "bar",
      "x": {
        "field": "start",
        "type": "genomic",
        "axis": "bottom",
        "linkingId": "1"
      },
      "xe": {"field": "end", "type": "genomic"},
      "y": {
        "field": "peak",
        "type": "quantitative",
        "axis": "left",
        "flip": false
      },
      "color": {"value": "#CC7DAA"},
      "stroke": {"value": "white"},
      "strokeWidth": {"value": 0.2},
      "style": {"background": "lightgray", "backgroundOpacity": 0},
      "width": 700,
      "height": 400
    }
  ]
}

https://user-images.githubusercontent.com/14843470/229638732-05fb2495-e01d-4396-a870-f3e11e195513.mov

The “showMousePosition” and “mousePositionColor” options in gosling-theme. https://github.com/gosling-lang/gosling-theme/blob/d438f77ed244eb04a4982891729b572d61285a5a/src/dark.ts#L22

From @sehilyi

The mouse positions are implemented in HiGlass, and we are using HiGlass’ track option (showMousePosition) to show the line in Gosling tracks. Unsure why it is not shown correctly. FYI, showMousePosition in HiGlass: https://docs.higlass.io/view_config.html