Bug 198504 The same name aggregation should be hint in dialog[0001]
Description: The same name aggregation should be hint in dialog[0001] Step: 1.New a datasource, dataset, table and binding the dataset. 2.New a aggregation column binding on table named aggr1. 3.Drop a aggregation item into table and set the named as aggr1. 4.Click OK Actual result: Pop up an error message said that the name is exist. Expected result: It can hint in dialog when input the same name, but pop up an error dialog
xtab/org.eclipse.birt.report.item.crosstab.ui/src/org/eclipse/birt/report/item/crosstab/internal/ui/dialogs/CrosstabBindingDialogHelper.java
{
		if ( getBinding( ) == null )
		{
			setTypeSelect( dataTypes[0] );
			this.newBinding = StructureFactory.newComputedColumn( getBindingHolder( ),
					isAggregate( ) ? DEFAULT_AGGREGATION_NAME
							: DEFAULT_ITEM_NAME );
			setName( this.newBinding.getName( ) );
		}
		else
		{
			setName( getBinding( ).getName( ) );
			setDisplayName( getBinding( ).getDisplayName( ) );
			setTypeSelect( DATA_TYPE_CHOICE_SET.findChoice( getBinding( ).getDataType( ) )
					.getDisplayName( ) );
			setDataFieldExpression( getBinding( ).getExpression( ) );
		}
		if ( this.getBinding( ) != null )
		{
			this.txtName.setEnabled( false );
		}
		if ( isAggregate( ) )
		{
			initFunction( );
			initDataFields( );
			initFilter( );
			initAggOn( );
		}
	}
	private void initAggOn( )