Bug 390669 [Accessibility]Press 'Tab' doesn't focus on the next report item when adding relative period aggregation.
xtab/org.eclipse.birt.report.item.crosstab.ui/src/org/eclipse/birt/report/item/crosstab/internal/ui/dialogs/CrosstabBindingDialogHelper.java
if ( !hasModified && isEditModal( ) )
			dialog.setCanFinish( false );
		else
			dialog.setCanFinish( true );
	}
	public boolean differs( ComputedColumnHandle binding )
	{
		if ( isAggregate( ) )
		{
			if ( !strEquals( binding.getName( ), txtName.getText( ) ) )
				return true;
			if ( !strEquals( binding.getDisplayName( ),
					txtDisplayName.getText( ) ) )
				return true;
			if ( !strEquals( binding.getDisplayNameID( ),
					txtDisplayNameID.getText( ) ) )
				return true;
			if ( !strEquals( binding.getDataType( ), getDataType( ) ) )
				return true;
			try
			{
				if ( !strEquals( DataAdapterUtil.adaptModelAggregationType( binding.getAggregateFunction( ) ),
						getFunctionByDisplayName( cmbFunction.getText( ) ).getName( ) ) )
					return true;
			}
			catch ( AdapterException e )
			{
			}
			if ( !exprEquals( (Expression) binding.getExpressionProperty( ComputedColumn.FILTER_MEMBER )
					.getValue( ),