This is a sample and useful customization. It's used to show tasks related to Dates with other
color and with a tooltip showing the task quantity. You can use the factory class
{@link net.sf.nachocalendar.tasks.TaskCalendarFactory} to create {@link net.sf.nachocalendar.components.DateField},
{@link net.sf.nachocalendar.components.DatePanel} and {@link net.sf.nachocalendar.components.CalendarPanel} components customized this way.