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
boolean found = false;
				for ( int i = 0; i < columns.length; i++ )
				{
					if ( DEUtil.getColumnExpression( columns[i] )
							.equals( handle.getValueExpr( ) ) )
					{
						found = true;
						break;
					}
				}
				if ( !found )
				{
					try
					{
						handle.setValueExpr( null );
					}
					catch ( SemanticException e )
					{
						ExceptionHandler.handle( e );
					}
				}
			}
			if ( newParameter == null )
			{
				newParameter = DesignElementFactory.getInstance( )
						.newScalarParameter( null ); 
				try
				{
					newParameter.setControlType( DesignChoiceConstants.PARAM_CONTROL_LIST_BOX );
					newParameter.setValueType( DesignChoiceConstants.PARAM_VALUE_TYPE_DYNAMIC );