title: Set default Home app dynamically
body: <p>Can I set dynamically within an activity the preferred/default application that's to be launched when I push the Home key?  If that's not possible, can I at least reset current defaults so that the chooser window re-appears?  I tried to implement the latter by calling PackageManager.clearPackagePreferredActivities("com.android.launcher"), but that doesn't seem to do it(I gave my activity SET_PREFERRED_APPLICATIONS permission).</p>