Bug 151960 Library element popup menu display is wrong.
1:Creat a libray, add a table to this libray. 2:public this library. 3:Creat a report design. 4:Open the library explore, drag the table to the layout editor. 5:Select the table row, copy the selection row. 6:Select other row, clik the right button of the mouse to popup the menu . The result:Paste action and insert copied column action is highlight.
model/org.eclipse.birt.report.model/src/org/eclipse/birt/report/model/api/ColumnBandAdapter.java
if ( columnToInsert == cellPos )
				return cell;
			
			
			else if ( columnToInsert < cellPos + cell.getColumnSpan( ) )
				return cell;
		}
		
		return null;
	}
	/**
	 * Returns the number of rows in the element.
	 * 
	 * @return the number or rows in the element.
	 */
	abstract protected int getRowCount( );
	/**
	 * Checks whether any cell in <code>cells</code> has a value of
	 * <code>DesignChoiceConstants#DROP_TYPE_DETAIL</code> or
	 * <code>DesignChoiceConstants#DROP_TYPE_ALL</code> for the "drop"
	 * property.
	 * 
	 * @param cells
	 *            a list containing cell handles
	 * @return <code>true</code> if any cell has the "drop" property,
	 *         otherwise <code>false</code>.
	 */
	abstract protected boolean hasDroppingCell( List cells );
	/**
	 * Returns copied cells with the column number.