Order of layering affect bar bandwidth

[joelostblom]

I want to use multiple aggregated tooltips with a box plot, but #7918 is preventing me from using the boxplot mark for this so I am building the chart from scratch. I noticed that the order of layering objects changes the bar bandwidth in an unfortunate way. If I put the line under the bar (as desired), there are not spaces between the bars:

Open the Chart in the Vega Editor

If the line goes on top, the spaces are there as intended:

Open the Chart in the Vega Editor

It feels like a bug to me that this is changed depending on the order of the charts in the layering. Looking at the vega spec, we can see that the first chart has "update": "bandspace(domain('x').length, 0, 0) * x_step"} and the second one has "update": "bandspace(domain('x').length, 0.1, 0.05) * x_step". A workaround is to set "mark": {"type": "bar", "width": {"band": 0.8}},