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 ( element instanceof ScalarParameterHandle )
			{
				ScalarParameterHandle parameter = (ScalarParameterHandle) element;
				String value = null;
				if ( COLUMN_NAME.equals( property ) )
				{
					if ( element == newParameter )
					{
						value = ""; 
					}
					else
					{
						value = parameter.getName( );
					}
				}
				else if ( COLUMN_DATA_SET.equals( property ) )
				{
					if ( isSingle( )
							&& inputParameterGroup.getDataSet( ) != null )
					{
						value = inputParameterGroup.getDataSet( ).getName( );
					}
					else if ( getDataSet( parameter ) != null )
					{
						value = getDataSet( parameter ).getName( );
					}
				}
				else if ( COLUMN_VALUE.equals( property ) )
				{