Volcano Plot: hover label is always the first input column; expose a Hover column property like Scatter Plot #9038

Feature Summary

VolcanoPlotOpDesc.scala:117 sets hover_name=table.columns[0]. Whatever column happens to be first in the upstream schema becomes the tooltip label. For a DESeq2 result table whose first column is gene this works by accident; for a DaPars2 result whose first column is a composite transcript|gene|chr|strand string, or any table that starts with a numeric column, the hover text is useless and there is no way to change it.

Scatter Plot already has a Hover column property (ScatterplotOpDesc.scala:90-94) that does exactly this.

Proposed Solution or Design

The same optional Hover column property on Volcano Plot, one column only; empty keeps the first column so existing workflows are unchanged.

Affected Area

No response