Bug 153387 Database item can't be dragged and dropped onto editor field
Steps to reproduce: 1.Start up BIRT in Mac OS X; 2.File->New->Project; 3.File->New->Report Design; 4.In Data Explorer, create a New Data Source, and choose "Classic Models Inc. Sample DataBase", press "Next" and then press "finish"; 5.In Data Explorer, create a New Data Set, press "Next"; 6.In the popup window, expand the "CLASSICMODELS", select and drag a item onto the editor field at right side.
data/org.eclipse.birt.report.data.oda.jdbc.ui/src/org/eclipse/birt/report/data/oda/jdbc/ui/editors/SQLDataSetEditorPage.java
if ( items != null )
						{
							for ( int i = 0; i < items.length; i++ )
							{
								items[i].dispose( );
							}
						}
						Utility.createTreeItems( item,
								columnList,
								SWT.NONE,
								columnImage );
					}
				}
			}
		} );
	}
	
	/**
	 * Adds drag support to tree..Must set tree before execution.
	 */
	public void addDragSupportToTree( )
	{
		DragSource dragSource = new DragSource( availableDbObjectsTree, DND.DROP_COPY );
		dragSource.setTransfer( new Transfer[]{TextTransfer.getInstance( )} );
		dragSource.addDragListener( new DragSourceAdapter( ) {
			public void dragStart( DragSourceEvent event )
			{
				TreeItem[] selection = availableDbObjectsTree.getSelection( );
				if ( selection.length > 0 )
				{