<p>I would like to break a long line of text assigned to the standard Label widget in GWT.
I was experimenting with inline <code>&lt;br /&gt;</code> elements but with no success.</p>

<p>Something like this: </p>

<pre><code>label = "My very very very long&lt;br /&gt;long long text"
</code></pre>

You need to use the HTML widget, which extends the standard Label widget, and adds support for interpreting HTML tags.
See the
JavaDoc
.