@Override
    public void setEnabled(final boolean enabled) {
        super.setEnabled(enabled);
        if (enabled) {
            getElement().removeClassName("Button--disabled");
        } else {
            getElement().addClassName("Button--disabled");
        }
    }
Gets the mouse y-position relative to a given element.

@param target the element whose coordinate system is to be used
@return the relative y-position
stroom-core-client-widget/src/main/java/stroom/widget/button/client/Button.java