Vaadin Grid, or dialog, headline overlaps content

Hello all

I am new on vaadin. I work with RapidClipse X and generated an application which has a strange behavior, which I am not able to fix.
I have a dialog with a combobox in it. When I open the content, it is shown in the background. The same behavior is in a grid.
There I open a second grid inline. It opens and the headline is in the front of the gridcontent.
Attached you will find two screenshots, which shows the behavior.

My pom.xml:

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
	<modelVersion>4.0.0</modelVersion>
	<groupId>com.rieder</groupId>
	<artifactId>finmgmt</artifactId>
	<packaging>war</packaging>
	<name>FinMgmt</name>
	<version>1.0.0.-SNAPSHOT</version>
	<build>
		<plugins>
			<plugin>
				<groupId>org.apache.maven.plugins</groupId>
				<artifactId>maven-compiler-plugin</artifactId>
				<version>3.8.0</version>
				<configuration>
					<source>1.8</source>
					<target>1.8</target>
				</configuration>
			</plugin>
			<plugin>
				<artifactId>maven-war-plugin</artifactId>
				<version>3.2.2</version>
				<configuration>
					<warName>${project.name}</warName>
					<failOnMissingWebXml>false</failOnMissingWebXml>
				</configuration>
			</plugin>
		</plugins>
	</build>
<profiles>
    <profile>
        <id>production</id>
        <properties>
            <vaadin.productionMode>true</vaadin.productionMode>
        </properties>
        <dependencies>
            <dependency>
                <groupId>com.vaadin</groupId>
                <artifactId>flow-server-production-mode</artifactId>
            </dependency>
        </dependencies>
    </profile>
    <profile>
        <id>development</id>
        <properties>
            <vaadin.productionMode>false</vaadin.productionMode>
        </properties>
        <dependencies>
            <dependency>
                <groupId>com.vaadin</groupId>
                <artifactId>flow-server-compatibility-mode</artifactId>
            </dependency>
        </dependencies>
    </profile>
</profiles>
	<repositories>
		<repository>
			<id>sonatype-nexus-snapshots</id>
			<name>Sonatype Nexus Snapshots</name>
			<url>
				https://oss.sonatype.org/content/repositories/snapshots
			</url>
			<releases>
				<enabled>false</enabled>
			</releases>
			<snapshots>
				<enabled>true</enabled>
			</snapshots>
		</repository>
	</repositories>
	<dependencies>
		<dependency>
			<groupId>com.rapidclipse</groupId>
			<artifactId>rap-server-core</artifactId>
			<version>10.02.01-RAP-GA</version>
		</dependency>
		<dependency>
			<groupId>com.rapidclipse</groupId>
			<artifactId>rap-server-persistence-jpa</artifactId>
			<version>10.02.01-RAP-GA</version>
		</dependency>
		<dependency>
			<groupId>mysql</groupId>
			<artifactId>mysql-connector-java</artifactId>
			<version>8.0.15</version>
		</dependency>
		<dependency>
			<groupId>com.rapidclipse</groupId>
			<artifactId>rap-server-security-auth</artifactId>
			<version>10.02.01-RAP-GA</version>
		</dependency>
		<dependency>
			<groupId>com.rapidclipse</groupId>
			<artifactId>rap-server-security-auth-jpa</artifactId>
			<version>10.02.01-RAP-GA</version>
		</dependency>
		<dependency>
			<groupId>commons-codec</groupId>
			<artifactId>commons-codec</artifactId>
			<version>1.11</version>
		</dependency>
		<dependency>
			<groupId>org.projectlombok</groupId>
			<artifactId>lombok</artifactId>
			<version>1.18.12</version>
		</dependency>
		<dependency>
			<groupId>com.rapidclipse</groupId>
			<artifactId>rap-server-reports</artifactId>
			<version>10.02.01-RAP-GA</version>
		</dependency>
		<dependency>
			<groupId>com.vaadin</groupId>
			<artifactId>vaadin-themes</artifactId>
			<version>8.10.3</version>
		</dependency>
		<dependency>
			<groupId>com.vaadin</groupId>
			<artifactId>vaadin-core</artifactId>
			<version>14.1.25</version>
		</dependency>
		<dependency>
			<groupId>com.vaadin</groupId>
			<artifactId>vaadin</artifactId>
			<version>14.1.25</version>
		</dependency>
		<dependency>
			<groupId>org.slf4j</groupId>
			<artifactId>slf4j-api</artifactId>
			<version>1.7.30</version>
		</dependency>
		<dependency>
			<groupId>org.slf4j</groupId>
			<artifactId>slf4j-jdk14</artifactId>
			<version>1.7.30</version>
		</dependency>

	</dependencies>
	<properties>
		<project.build.sourceEncoding>
			UTF-8
		</project.build.sourceEncoding>
	</properties>
</project>

Additional: There is a compiler warning while deploying:

Apr. 22, 2020 7:35:07 NACHM. com.vaadin.flow.server.DefaultDeploymentConfiguration checkProductionMode
WARNING: 
====================================================================
Vaadin is running in DEBUG MODE.
In order to run your application in production mode and disable debug features, you should enable it by setting the servlet init parameter productionMode to true.
See https://vaadin.com/docs/v14/flow/production/tutorial-production-mode-basic.html for more information about the production mode.
====================================================================
Apr. 22, 2020 7:35:07 NACHM. com.vaadin.flow.server.DefaultDeploymentConfiguration checkCompatibilityMode
WARNING: 
====================================================================
Running in Vaadin 13 (Flow 1) compatibility mode.
This mode uses webjars/Bower for client side dependency management and HTML imports for dependency loading.
The default mode in Vaadin 14+ (Flow 2+) is based on npm for dependency management and JavaScript modules for dependency inclusion.

Below you will find the sample for my modal dialog:

private void btEditL1_onClick(final ClickEvent<Button> event)
	{
		//modal Dialog Mainclassification
		final HorizontalLayout horlayout=new HorizontalLayout();
		final VerticalLayout vertlayout=new VerticalLayout();
		final Notification MyL1Selection=new Notification();//
		final Button btnAbbruch=new Button();
		final ComboBox<TfinGroup> cBL1Liste = new ComboBox<>();

		//		btnFertig.setText("Done");
		btnAbbruch.setText("Cancel");
		vertlayout.add(new Label("Please select a class"));
		horlayout.add(cBL1Liste);
		horlayout.add(btnAbbruch);
		//		horlayout.add(btnFertig);
		vertlayout.add(horlayout);
		
		cBL1Liste.setDataProvider(DataProvider.ofCollection(TfinGroupDAO.INSTANCE.findMainGroups()));
		cBL1Liste.setItemLabelGenerator(ItemLabelGeneratorFactory
			.NonNull(v -> CaptionUtils.resolveCaption(v, "{%id}, {%groupName}")));



		
		cBL1Liste.addValueChangeListener(evtChangeSelektion ->
		{
			this.logger.info("a selection was done: "+ evtChangeSelektion.getValue().getId());
			this.nrL1Id.setValue((double)evtChangeSelektion.getValue().getId());
			MyL1Selection.close();
			
		});
		
		btnAbbruch.addClickListener(evtclose->
		{
			this.logger.info("canceled clicked");
			MyL1Selection.close();
		});


		vertlayout.add(horlayout);
		horlayout.add(btnAbbruch);

		MyL1Selection.add(vertlayout);
		MyL1Selection.setPosition(Position.MIDDLE);
		MyL1Selection.addThemeVariants(NotificationVariant.LUMO_PRIMARY);
		MyL1Selection.open();
		this.btnEditL2.setVisible(true);

	}

It would be fine, if someone can give me a hint, how I can fix this issue.
Thank you in advance
Heinz

18226875.png
18226878.jpg