Important Notice - Forums is archived
To simplify things and help our users to be more productive, we have archived the current forum and focus our efforts on helping developers on Stack Overflow. You can post new questions on Stack Overflow or join our Discord channel.

Vaadin lets you build secure, UX-first PWAs entirely in Java.
Free ebook & tutorial.
Jetty embedded + Vaadin + Add-on
Hello.
I try to learn how to make own add-ons.
I try to use that add-on: http://vaadin.com/directory#!addon/client-side-confirm-button
I was make these steps:
1. Download sources from GITHub (https://github.com/daniel-sc/vaadin-client-side-confirm-button)
2. Extract sources to classpath of existing project. Extract these files:
- ConfirmButtonWidgetset.gwt.xml
- ConfirmButton.java
client/ConfirmButtonConnector.java
client/ConfirmButtonState.java
3. Add new component:
ConfirmButton button = new ConfirmButton("Save to click");
button.addClickListener(e -> System.out.println("Button was clicked and confirmed"));
button.setCancelButtonIcon(FontAwesome.TIMES);
button.setConfirmButtonIcon(FontAwesome.CHECK_CIRCLE);
button.setConfirmQuestion("Are you really sure?");
button.setConfirmText("I am sure!");
button.setCancelText("I am not really sure..");
horizontalLayout.addComponent(button);
4. From Maven start "package"
5. Start application
In the result: i can see this Button, can click on it and view System.out.println() messages on Java console.
But i can't get to show any confirmation elements.
I'm newby Vaadin-developer and may it be i loose some need steps?
Wait. I try to add this ConfirmButton over Maven and recompile project, but there is same problems.
Then i try to add over Maven another add-on https://vaadin.com/directory#!addon/messagebox
It works well.
Then i try to disable Maven dependency and download sources of MessageBox.
After adding sources to project and recompile them it works well.
May it be that ConfirmButton contains bug?