Understanding SiteMesh part of Scaffolding wizard

decorators.xml seems to set the rules of which files to decorate

I noticed that the decorator tag appears to be used in order to implement the SiteMesh formatting but why are there references to undefined .css files e.g
<style type=”text/css” media=”screen”>
@import url(“${pageContext.request.contextPath}/resources/dojo/resources/dojo.css”);
@import url(“${pageContext.request.contextPath}/resources/dijit/themes/tundra/tundra.css”);
</style>
within main.jsp such files do not exist but the classes are supposedly used in the body for example. Is the the correct way to use SiteMesh PageFilter and do you have plans to upgrade considering that object was depprecated by OpenSymphony?
Also
In Scaffolding projects what does this mean in main.jsp ???:
<decorator:head /> ?? applied to the head tag how?
<decorator:body /> ?? Applied to body tag how?
or in panel.jsp :
<decorator:title default=”Unknown panel” />
Which of the following files are used here of the following to realize the intended functionality:
dashboard.jsp
footer.jsp
header.jsp
login.jsp
tabs.jsp
————-
include.jsp
main.jsp
panel.jsp
printable.jsp

? It does not make a lot of sense as to how these files are used to format pages
A little help here would go a long way!