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
String str = getFirstUseDimensonDisplayName( );
			if ( str != null && str.length( ) > 0 )
			{
				int itemIndex = getItemIndex( strs, str );
				if ( itemIndex >= 0 )
				{
					timeDimension.select( itemIndex );
				}
				else
				{
					timeDimension.select( 0 );
				}
			}
			else
			{
				timeDimension.select( 0 );
			}
		}
		else
		{
			String value = getBinding( ).getTimeDimension( );
			int itemIndex = getItemIndex( strs, value );
			timeDimension.select( itemIndex );
		}
	}
	private String getFirstUseDimensonDisplayName( )
	{
		CrosstabReportItemHandle crosstab = getCrosstabReportItemHandle( );
		int count = crosstab.getDimensionCount( ICrosstabConstants.COLUMN_AXIS_TYPE );
		for ( int i = 0; i < count; i++ )