setPrimaryStyleName not reflected in the DOM when using FireFox


I encounteres an issue when using FireFox.
The issue is inconsistent and occurs randomly.

I implemented a layout component which extends AbsoluteLayout.
The component also has a JS extension which extends AbstractJavaScriptExtension.

In the constructor of the layout I call setPrimaryStyleName(className).
After setting the style I extend the layout using the JS extension.
In my client side code I look for the div with my className but for some reason when my client code is executed the div classname is still .v-absolutelayout.
After a short while the div’s class name is updated with my given class name.

I expected that since I call the setPrimaryStyleName in the constructor the div will be created with that class name.
Do you have any idea what might be the issue?

I’m using Vaadin 7.2.5 and FireFox 41.0.2.