Whether to lay out the plot with a horizontal value axis (bottom) and a vertical category axis (left), instead of the default vertical value axis (left) / horizontal category axis (bottom). Default: false. Overridden by BarChart based on BarOptions::orientation; not meaningful for Line/Area/Combo's point-based geometry, so they don't override it. ReferenceLine / ReferenceBand overlays are not supported in horizontal mode (v1) since their orientation semantics assume a vertical value axis.
<insightdock/cartesian_chart.h>
virtual
bool
is_horizontal() const;