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
* 
	 * @param parent
	 * @param text
	 * @return tree item
	 */
	private TreeItem createTopTreeItem( Tree parent, String text )
	{
		TreeItem item = new TreeItem( parent, SWT.NONE );
		item.setText( text );
		item.setImage( IMAGE_FOLDER );
		item.setData( ITEM_DATA_KEY_TOOLTIP, "" );
		return item;
	}
	private TreeItem createSubTreeItem( TreeItem parent, String text,
			Image image, boolean isEnabled )
	{
		return createSubTreeItem( parent, text, image, null, text, isEnabled );
	}
	private TreeItem createSubTreeItem( TreeItem parent, String text,
			Image image, String textData, String toolTip, boolean isEnabled )
	{
		TreeItem item = new TreeItem( parent, SWT.NONE );
		item.setText( text );
		if ( image != null )
		{
			item.setImage( image );
		}
		item.setData( ITEM_DATA_KEY_TOOLTIP, toolTip );
		item.setData( ITEM_DATA_KEY_TEXT, textData );
		item.setData( ITEM_DATA_KEY_ENABLED, new Boolean( isEnabled ) );