public boolean isReadOnly() {
        return getElement().getPropertyBoolean("readOnly");
    }
Determines whether or not the widget is read-only.

@return <code>true</code> if the widget is currently read-only,
<code>false</code> if the widget is currently editable
stroom-core-client-widget/src/main/java/com/google/gwt/user/client/ui/ValueBoxBase.java