Bug 166015 Refactor designer actions to eclipse command framework
Eclipse command framework provide a more explicit way to manage UI actions contributions, we can take it's advantage to make our actions code more clean and maintainable.
UI/org.eclipse.birt.report.designer.ui/src/org/eclipse/birt/report/designer/internal/ui/views/actions/DeleteAction.java
return true;
		}
		else if ( model instanceof DesignElementHandle )
		{
			DesignElementHandle handle = (DesignElementHandle) model;
			if ( handle instanceof ParameterGroupHandle )
			{
				if ( ( (ParameterGroupHandle) handle ).getParameters( )
						.getCount( ) > 0 )
				{
					if ( !MessageDialog.openQuestion( PlatformUI.getWorkbench( )
							.getDisplay( )
							.getActiveShell( ),
							CONFIRM_PARAM_DELETE_TITLE,
							CONFIRM_PARAM_DELETE_MESSAGE ) )
					{
						return false;
					}
					for ( Iterator iter = ( (ParameterGroupHandle) handle ).getParameters( )
							.iterator( ); iter.hasNext( ); )
					{
						Object obj = iter.next( );
						if ( obj instanceof ParameterHandle )
						{
							ParameterHandle parameter = (ParameterHandle) obj;
							ConfigVariable cv = parameter.getModuleHandle( )
									.findConfigVariable( parameter.getName( ) );
							try
							{
								if ( cv != null )