The editor:
Has the following functions/options.
You can type into it to create your pseudo html page. or a template for use as an include file. For example, the file above will create the following looking html page after compilation:

All that from such simple text!
It's not magic. The text is:
<<header.inc>>
<<main.inc>>
{{images/ray.jpg}}
{{images/ray_section.jpg}}
<<footer.inc>>
The first line includes the file 'header.inc' which includes the headers, all the way down to the 'quick links' menu on the left of the web page. The menu is stored in the 'main.inc' file. Two images are displayed, followed by the footer stored in 'footer.inc'.
Of course the page uses a stylesheet to obtain formatting and the 'main.inc' file stops at such a place in the text stream that the images and any other artifacts are introduced in a table on the right of the page. 'footer.inc' closes that table etc.
Back to the editor. You may cut/paste as expected, and search/replace with the search button on the editor's toolbar:
Pressing this will give you the search/replace dialog:
Syntax highlighting can be turned on/off with the 'Syntax HL' checkbox, also on the editor's toolbar.
And lastly, you can insert a sitemap into the source by right clicking on the editor and choosing the 'Insert sitemap' menu option: