Bug 136270 Group's data binding column can only be used by the group itself
If you add some data binding columns to a group, these columns can only be used by this group itself. It should has a way to make the child can use the parent group's data binding column.
UI/org.eclipse.birt.report.designer.core/src/org/eclipse/birt/report/designer/util/DEUtil.java
units = dimension.getUnits( );
		}
		if ( DesignChoiceConstants.UNITS_PX.equals( units ) )
		{
			return measure;
		}
		
		if ( "".equalsIgnoreCase( units ) ) 
		{
			px = measure;
		}
		if ( fontSize == 0 )
		{
			Font defaultFont = JFaceResources.getDefaultFont( );
			FontData[] fontData = defaultFont.getFontData( );
			fontSize = fontData[0].getHeight( );
		}
		if ( DesignChoiceConstants.UNITS_EM.equals( units ) )
		{
			px = DimensionUtil.convertTo( measure * fontSize,
					DesignChoiceConstants.UNITS_PT,
					DesignChoiceConstants.UNITS_IN ).getMeasure( );
		}
		else if ( DesignChoiceConstants.UNITS_EX.equals( units ) )
		{
			px = DimensionUtil.convertTo( measure * fontSize / 3,
					DesignChoiceConstants.UNITS_PT,
					DesignChoiceConstants.UNITS_IN ).getMeasure( );
		}
		else if ( DesignChoiceConstants.UNITS_PERCENTAGE.equals( units ) )