While a page, index.zul,for instance, using <include> like:
<include src="included.zul" mode="defer"/>
and there are some components, <textbox/> <intbox/> <window/> <panel/> <style/> <vbox/> as known, inside the included page,
the index page will be stay at "loading" state.
But <include> will work without mode="defer", or there are already "the same kind" of tags inside the index.zul.