Android :: Setting Application - Wide Themes

I have created several files in a res/values/styles.xml file.

Here's one of them:

CODE:..............

I can apply the style to a single element in the xml by setting the style element like this:

CODE:.................

So, that works, and I notice that change. But what I really want to do is use the style above to apply to my entire application. I thought I'd be able to use this line:

this.getApplicationContext().setTheme(R.style.BlueOnWhite);

Before the super.onCreate of the first activity. But it doesn't work. Should it?