Bug 155365 Can not set data type to "date time" when editing "Data Item"
Description: Can not set data type to "date time" when editing "Data Item" Steps to reproduce: 1. Insert a data item to the layout 2. Name it and set the expression to "a = new Date()" 3. Select the data type to date time 4. Press ok Actual result: An Birt Exception is thrown out. Expected result: No NPE thrown out
UI/org.eclipse.birt.report.designer.ui/src/org/eclipse/birt/report/designer/ui/dialogs/ColumnBindingDialog.java
String[] dataSets = ChoiceSetFactory.getDataSets( );
			String[] newList = new String[dataSets.length + 1];
			newList[0] = NullChoice;
			System.arraycopy( dataSets, 0, newList, 1, dataSets.length );
			combo.setItems( newList );
			String dataSetName = getDataSetName( );
			combo.deselectAll( );
			if ( dataSetName != null )
			{
				combo.setText( dataSetName );
			}
			else
			{
				combo.select( 0 );
			}
			combo.setLayoutData( new GridData( GridData.FILL_HORIZONTAL ) );
			gd = new GridData( );
			gd.widthHint = 250;
			combo.setLayoutData( gd );
			combo.addSelectionListener( new SelectionAdapter( ) {
				public void widgetSelected( SelectionEvent event )
				{
					String value = null;
					if ( combo.getSelectionIndex( ) != 0 )
					{
						value = combo.getText( );
					}
					int rCode = canChangeDataSet( value );
					if ( rCode == 2 )
					{