メモ：ViewStub は merge タグ不可

ViewStub では merge タグでレイアウトXMLを定義することはできない

http://developer.android.com/resources/articles/layout-tricks-stubs.html

A ViewStub is a great compromise between ease of programming and efficiency. 
Instead of inflating views manually and adding them at runtime to your view hierarchy, 
simply use a ViewStub. It's cheap and easy. The only drawback of ViewStub is that 
it currently does not support the <merge /> tag.

ViewStub 用のXMLファイルをLinearLayoutで書いた場合の擬似コード

        ViewStub hogeViewStub = (ViewStub)findViewById(R.id.hogeViewStub);
        hogeViewStub.setLayoutResource(R.layout.stub_parts_hoge);
        hogeViewStub.inflate();
        hogeView = (HogeView)findViewById(R.id.hogeView);