Bug 154832 Wrong node is added to Report Parameters for cascading parameter in Palette view
Description: Wrong node is added to Report Parameters for cascading parameter in Palette view. Steps to reproduce: 1. New a report, add a cascading parameter 2. Switch to Script tab in Editor view, and then switch to Palette view 3. Expand Report Parameters node Expected result: A cascading parameter group is added to Report Parameters node Actual result: Expect a cascading parameter group is added to Report Parameters node, the children of the cascading parameter group are added as scalar parameters
UI/org.eclipse.birt.report.designer.ui/src/org/eclipse/birt/report/designer/internal/ui/dialogs/ExpressionTreeSupport.java
DesignElementHandle handle = (DesignElementHandle) currentEditObject;
			Map argMap = DEUtil.getDesignElementMethodArguments( handle,
					methodName );
			for ( Iterator iter = argMap.keySet( ).iterator( ); iter.hasNext( ); )
			{
				String argName = (String) iter.next( );
				createSubTreeItem( contextItem,
						argName,
						IMAGE_METHOD,
						argName,
						"", 
						true );
			}
		}
	}
	public void setCurrentEditObject( Object obj )
	{
		this.currentEditObject = obj;
		removeTreeItem( );
	}
	
	private void removeTreeItem( )
	{
		if ( contextItem == null || contextItem.isDisposed( ) )
			return;
		TreeItem[] items = contextItem.getItems( );
		for ( int i = 0; i < items.length; i++ )
		{
			if ( items[i] != null && !items[i].isDisposed( ) )
			{