Appending footer rows during attach causes event handlers to fire multiple times

[eriklumme]

In a Grid with a TemplateRenderer that has an event handler, the event handler is fired multiple times on each event, if more than one footer row is appended during the grid's attach event.

Complete example

@Route("footer")
public class FooterRowTest extends Div {

    public FooterRowTest() {
        Grid<String> grid = new Grid<>();
        grid.addColumn(
                TemplateRenderer.<String>of("<span on-click=foo>Click me</span>")
                        .withEventHandler("foo",
                                item -> Notification.show(item, 3000, Notification.Position.TOP_CENTER)));
        grid.setItems("Test");
        add(grid);

        grid.addAttachListener(e -> {
            grid.appendFooterRow();
            grid.appendFooterRow();
        });
    }
}

Steps to reproduce

In the example, click the only item in the grid.

Expected outcome

One notification is shown

Actual outcome

Two notifications are shown

Versions

Platform 13.0.2, Chrome 73

[eriklumme]

Adding just one footer row does not seem to have an affect, likely because the first call reuses an existing column layer.

I have not been able to reproduce this by adding footer rows before or after the attach event.