Bug 190727 [regression]Default value issue when switch report parameter from textbox to listbox.[0705]
UI/org.eclipse.birt.report.designer.ui/src/org/eclipse/birt/report/designer/ui/dialogs/ParameterDialog.java
createDataSet = new Button( composite, SWT.PUSH );
		createDataSet.setText( BUTTON_CREATE_DATA_SET );
		setButtonLayoutData( createDataSet );
		createDataSet.addSelectionListener( new SelectionAdapter( ) {
			public void widgetSelected( SelectionEvent e )
			{
				new NewDataSetAction( ).run( );
				refreshDataSets( );
			}
		} );
		createLabel( composite, LABEL_SELECT_VALUE_COLUMN );
		
		columnChooser = new Combo( composite, SWT.BORDER | SWT.DROP_DOWN );
		columnChooser.setLayoutData( new GridData( GridData.FILL_HORIZONTAL ) );
		columnChooser.addSelectionListener( new SelectionAdapter( ) {
			public void widgetSelected( SelectionEvent e )
			{
				updateButtons( );
			}
		} );
		Button valueColumnExprButton = new Button( composite, SWT.PUSH );
		
		UIUtil.setExpressionButtonImage( valueColumnExprButton );
		valueColumnExprButton.setToolTipText( Messages.getString( "ParameterDialog.toolTipText.OpenExprButton" ) );
		valueColumnExprButton.addSelectionListener( new SelectionAdapter( ) {
			public void widgetSelected( SelectionEvent event )
			{
				ExpressionBuilder expressionBuilder = new ExpressionBuilder( getExpression( columnChooser.getText( ) ) );
				expressionBuilder.setExpressionProvier( new ParameterExpressionProvider( inputParameter,
						dataSetChooser.getText( ) ) );