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/internal/ui/dialogs/ExpressionTreeSupport.java
*/
	public void setTree( Tree tree )
	{
		this.tree = tree;
	}
	protected Tree getTree( )
	{
		return tree;
	}
	/**
	 * Sets the viewer to use.
	 * 
	 * @param expressionViewer
	 */
	public void setExpressionViewer( SourceViewer expressionViewer )
	{
		this.expressionViewer = expressionViewer;
	}
	protected SourceViewer getExpressionViewer( )
	{
		return expressionViewer;
	}
	/**
	 * Gets an icon image by the key in plugin.properties
	 * 
	 * @param id
	 * @return image
	 */
	private static Image getIconImage( String id )
	{