Method prevPlot

src/plotViewer/index.ts:439–442

(first?: boolean)

        await this.focusPlot();
    }
    public async prevPlot(first?: boolean): Promise<void> {
        this.activeIndex = first ? 0 : this.activeIndex - 1;
        await this.focusPlot();
    }

    // restore closed plots, reset zoom, redraw html
    public resetPlots(): void {