I think that:

Application.get(ActionManager.class).getActionMap();
...

is not much better than:

Application.getInstance(...)...
...

both are ways to lookup singletons. Singletons are evil. It's better to leverage existing dependency injection frameworks to inject dependent resources, avoiding resource lookups and instead make SAF more DI framework friendly.

I'm quite successfully using SAF with Spring. I had to work arround the "Application as a singleton and it's own factory" design using hacks such as for example this:

public class SpringSingleFrameApplication extends SingleFrameApplication
{
public static final String MAIN_VIEW_BEAN_NAME = "mainView";

private String[] paths;

@Override
protected void initialize(String[] args)
{
    if (args == null || args.length == 0)
    throw new IllegalArgumentException("No arguments specified for Application.launch() method");

    paths = args;
}

@Override
protected void startup()
{
    ApplicationContext appCtx = new ClassPathXmlApplicationContext(paths, getClass());
    View mainView = (View) appCtx.getBean(MAIN_VIEW_BEAN_NAME, View.class);
    show(mainView);
}
}
...

...and then using the following to be able to "inject" Application instance into other components of my application:

public class ApplicationFactoryBean implements FactoryBean
{
@Override
public Object getObject() throws Exception
{
    return Application.getInstance();
}

@Override
public Class getObjectType()
{
    return Application.getInstance().getClass();
}

@Override
public boolean isSingleton()
{
    return true;
}
}
...

It would be nice to make BSAF more DI framework friendly than SAF. Currently it is impossible to break the singleton (I agree this is not something one would like to do). But at least it should be possible to construct new instance of Application using a DI framework of your choice.