The simple theme renders “bare bones” HTML elements. The simple theme is most often used as a starting point for other
themes. (See Extending Themes for more.)
For example, the textfield tag renders the HTML <input/> tag without a label, validation, error
reporting, or any other formatting or functionality.
Both the xhtml theme and css_xhtml theme extend the simple theme. Look
to them for examples of how to build on the foundation laid by the simple theme.
Head Tag
The simple theme head template prints out a javascript include required
for the datetimepicker tag to render properly.
simple head template
The simple themehead template only does one thing: it loads the minimal
Ajax/Dojo support so that tags can import Dojo widgets easily.