Bug 122869 Drag a parameter from data explorer view into a table in library, a new parameter is created automatically.
Description:Drag a parameter from data explorer view into a table in library, a new parameter is created automatically. Steps to reproduce: 1. Add a cascading parameter and a table in a library file. 2. Drag a parameter from data explorer view into a table cell in layout editor. 3. Find that a new parameter was added in data explorer view automatically.
UI/org.eclipse.birt.report.designer.ui/src/org/eclipse/birt/report/designer/ui/dialogs/ExpressionBuilder.java
* Create an expression builder under the given parent shell with the given
	 * initial expression
	 * 
	 * @param parentShell
	 *            the parent shell
	 * @param initExpression
	 *            the initial expression
	 */
	public ExpressionBuilder( Shell parentShell, String initExpression )
	{
		super( parentShell );
		title = DIALOG_TITLE;
		this.expression = UIUtil.convertToGUIString( initExpression );
	}
	/**
	 * Create an expression builder under the default parent shell with the
	 * given initial expression
	 * 
	 * @param initExpression
	 *            the initial expression
	 */
	public ExpressionBuilder( String initExpression )
	{
		this( UIUtil.getDefaultShell( ), initExpression );
	}
	/**
	 * Create an expression builder under the default parent shell without an
	 * initail expression
	 * 
	 */