private int getScrollBarTop() {
        if (isChrome()) {
            return 0;
        }

        return ScrollbarMetrics.getHorizontalScrollBarWidth();
    }
Redraws the overview bar. This is called when indicators are
added/removed, when indicators are set to be displayed and when the
widget is resized.
stroom-core-client-widget/src/main/java/stroom/editor/client/view/RightBar.java