Android Create Floating Window

private void initFloatingWindow() {
        mWindowManager = (WindowManager)mContext.getSystemService(Context.WINDOW_SERVICE);
        mWindow = PolicyManager.makeNewWindow(mContext);
        mWindow.setWindowManager(mWindowManager, null, null);
        mWindow.requestFeature(Window.FEATURE_NO_TITLE);
        mDecor = mWindow.getDecorView();
        mDecor.setOnTouchListener(mTouchListener);
        mWindow.setContentView(this);
        mWindow.setBackgroundDrawableResource(android.R.color.transparent);
        
        // While the media controller is up, the volume control keys should
        // affect the media stream type
        mWindow.setVolumeControlStream(AudioManager.STREAM_MUSIC);

        setFocusable(true);
        setFocusableInTouchMode(true);
        setDescendantFocusability(ViewGroup.FOCUS_AFTER_DESCENDANTS);
        requestFocus();
}

ref: MediaController.java