private double getWindowAsPercentage() {
        return getWindowSize() / getTotalSize() * 100;
    }
@param valueConsumer A consumer of the value of the point on the progress bar
                     that was clicked in the same units as used in {@link Progress}.
                     valueConsumer will not be called if the current value of {@link Progress}
                     has no upper bound.
stroom-core-client-widget/src/main/java/stroom/widget/progress/client/presenter/ProgressPresenter.java