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
createPromptLine( tableAreaComposite );
		updateTableButtons( );
	}
	private void switchToText( )
	{
		createDefaultEditor( );
		createLabel( valueArea, null );
		createPromptLine( valueArea );
	}
	private void switchToStatic( )
	{
		changeControlType( );
		listLimit.setEditable( false );
	}
	private void switchToDynamic( )
	{
		Composite composite = new Composite( valueArea, SWT.NONE );
		GridData gd = new GridData( GridData.FILL_HORIZONTAL );
		gd.horizontalSpan = 2;
		composite.setLayoutData( gd );
		composite.setLayout( UIUtil.createGridLayoutWithoutMargin( 3, false ) );
		createLabel( composite, LABEL_SELECT_DATA_SET );
		dataSetChooser = new Combo( composite, SWT.BORDER | SWT.READ_ONLY );
		dataSetChooser.setLayoutData( new GridData( GridData.FILL_HORIZONTAL ) );
		dataSetChooser.addSelectionListener( new SelectionAdapter( ) {
			public void widgetSelected( SelectionEvent e )
			{
				refreshColumns( false );
			}
		}