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/ParameterDialog.java
popupFormatBuilder( true );
			}
		} );
		createLabel( moreOptionSection, null );
		Group previewArea = new Group( moreOptionSection, SWT.NONE );
		previewArea.setLayoutData( new GridData( GridData.FILL_HORIZONTAL ) );
		previewArea.setLayout( UIUtil.createGridLayoutWithoutMargin( ) );
		previewArea.setText( LABEL_PREVIEW );
		previewLabel = new Label( previewArea, SWT.NONE );
		previewLabel.setAlignment( SWT.CENTER );
		previewLabel.setLayoutData( new GridData( GridData.FILL_HORIZONTAL ) );
		
		createLabel( moreOptionSection, LABEL_LIST_LIMIT ); 
		Composite limitArea = new Composite( moreOptionSection, SWT.NULL );
		GridLayout layout = new GridLayout( 2, false );
		layout.marginWidth = 0;
		layout.marginHeight = 0;
		limitArea.setLayout( layout );
		GridData data = new GridData( GridData.FILL_HORIZONTAL );
		data.verticalSpan = 1;
		limitArea.setLayoutData( data );
		listLimit = new Text( limitArea, SWT.BORDER );
		data = new GridData( );
		data.widthHint = 80;
		listLimit.setLayoutData( data );
		listLimit.addVerifyListener( new VerifyListener( ) {
			public void verifyText( VerifyEvent e )
			{
				e.doit = ( "0123456789\0\b\u007f".indexOf( e.character ) != -1 ); 
			}