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
if ( !isSingle( ) )
		{
			if ( handle.getDataSetName( ) != null )
			{
				return getDataSet( handle.getDataSetName( ) );
			}
			return null;
		}
		return inputParameterGroup.getDataSet( );
	}
	private DataSetHandle getDataSet( String name )
	{
		return inputParameterGroup.getModuleHandle( ).findDataSet( name );
	}
	private void setCellEditorItems( )
	{
		( (ComboBoxCellEditor) cellEditors[2] ).setItems( getDataSetColumns( selectedParameter,
				true ) );
		( (ComboBoxCellEditor) cellEditors[3] ).setItems( getDataSetColumns( selectedParameter,
				false ) );
	}
	private IStructuredContentProvider contentProvider = new IStructuredContentProvider( ) {
		public Object[] getElements( Object inputElement )
		{
			ArrayList elementsList = new ArrayList( inputParameterGroup.getParameters( )
					.getContents( ) );
			for ( Iterator iter = elementsList.iterator( ); iter.hasNext( ); )
			{
				ScalarParameterHandle handle = (ScalarParameterHandle) iter.next( );
				String[] columns = getDataSetColumns( handle, false );