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
* 
	 * @param columnNumber
	 *            the column number
	 * @return new cell instances
	 */
	protected List getCellsUnderColumn( int columnNumber )
	{
		return getCellsUnderColumn( columnNumber, true );
	}
	/**
	 * Returns copied cells with the column number regardless whether the
	 * current position is where the cell element begins to span.
	 * 
	 * 
	 * @param columnNumber
	 *            the column number
	 * @param mustBeStartPosition
	 *            <code>true</code> if it is. Otherwise <code>false</code>.
	 * @return the matched cell
	 */
	abstract protected List getCellsUnderColumn( int columnNumber,
			boolean mustBeStartPosition );
	/**
	 * Returns copied cells with the given slot and column number.
	 * 
	 * @param handle
	 *            the slot
	 * @param columnIndex
	 *            the column number
	 * @param mustBeStartPosition