Bug 153523 OK button in parameter dialog is enabled without default value in combo-box
Description: OK button in parameter dialog is enabled without default value in combo-box Steps to reproduce: 1. New a report parameter, combo-box. 2. Click New button, input abc as value, click OK 3. Set abc as default value and close Edit Parameter dialog. 4. New a data source and dataset 5. Edit the parameter, remove abc value and import values from dataset Expected result: OK button is disabled for there is no default value. Actual result: OK button is enabled.
UI/org.eclipse.birt.report.designer.ui/src/org/eclipse/birt/report/designer/ui/dialogs/CascadingParametersDialog.java
private static final String PARAM_CONTROL_COMBO = DesignChoiceConstants.PARAM_CONTROL_LIST_BOX
			+ "/Combo"; 
	private static final String DISPLAY_NAME_CONTROL_LIST = Messages.getString( "CascadingParametersDialog.display.controlType.listBox" ); 
	private static final String DISPLAY_NAME_CONTROL_COMBO = Messages.getString( "CascadingParametersDialog.display.controlType.comboBox" ); 
	private static final double DEFAULT_PREVIEW_NUMBER = Double.parseDouble( "1234.56" ); 
	private static final int DEFAULT_PREVIEW_INTEGER_NUMBER = 123456;
	private static final String DEFAULT_PREVIEW_STRING = Messages.getString( "CascadingParametersDialog.default.preview.string" ); 
	private static final String ERROR_TITLE_INVALID_LIST_LIMIT = Messages.getString( "ParameterDialog.ErrorTitle.InvalidListLimit" ); 
	private static final String ERROR_MSG_INVALID_LIST_LIMIT = Messages.getString( "ParameterDialog.ErrorMessage.InvalidListLimit" ); 
	private Group optionsGroup;
	private Group propertiesGroup;
	private Text cascadingNameEditor;
	private Text promptTextEditor;
	private Text paramNameEditor;
	private Text helpTextEditor;
	private Text defaultValueEditor;
	private Text formatField;
	private Text listLimit;
	private Text promptText;
	private Combo dataTypeChooser;
	private Combo displayTypeChooser;
	private Button changeFormat;
	private Button singleDataSet, multiDataSet;
	private Label previewLable;
	private Table table;
	private TableViewer valueTable;
	private CellEditor[] cellEditors;
	private static IChoiceSet dataType = DEUtil.getMetaDataDictionary( )
			.getChoiceSet( DesignChoiceConstants.CHOICE_PARAM_TYPE );
	private CascadingParameterGroupHandle inputParameterGroup;