This method returns a collection of org.eclipse.birt.chart.ui.swt.interfaces.IChartType objects that are used to
add entries (Chart types, subtypes etc.) to the Chart selector UI.
This method returns a collection of org.eclipse.birt.chart.ui.swt.interfaces.IChangeListener objects that listen
for changes to the model and accordingly call methods to add or remove sheets from the Chart Designer UI.
This method returns a collection of org.eclipse.birt.chart.ui.swt.interfaces.ISheet objects which are used to add
entries into the navigation tree in the Chart Designer and associate a property sheet with each.
This interface provides a mechanism whereby a custom UI sheet provider can register a class to manage addition and
removal of UI sheets dynamically based on changes in the model.