If you're new to the containment concept, one glance at a source chart and you're over the learning curve. Intermediate and advanced developers can save hours tracking down bugs in complex documents.
"...the most accessible DOM inspector available to web developers."
"(This) extension should be standard in every web developer's toolkit."
John Resig, creator of the jQuery JavaScript Library, from his book, Pro JavaScript Techniques.
View Source Chart works great as a visual aid tool for use in learning environments."this is a great quick debugging tool for me and a lifesaver of a learning tool for those i instruct. html is all about nested containers and this clearly shows them much better than all my commenting, indentation, or syntax coloring ever could."
Cheridy
Harvard University Graduate School of Design Instructor
By "reading" the chart's lines and colors side to side, one can visually navigate through the most complex document structure with ease."Even the most complicated nesting xhtml containers and hierarchies are so much easier to navigate that it's almost laughable."
Dewey Spencer
A Right click on a web page and select "View Source Chart" from the context menu.
To view a frameset document, select "View Source Chart" from Fx's View menu.
To Use Collapse/Expand Feature:
Click on an opening tag to collapse its box, and anywhere in the collapsed box to expand.
With practice, you'll learn all the clickable spots, namely; anywhere within a container except on indented tags.
This allows you collapse a container from its side or bottom.
Scroll Into View Collapsibility:
If a container is collapsed from its bottom or side (the container top is out of view), the document is scrolled up and positioned just above the top of the newly collapsed container, enabling you to keep your place.
To Open Source Charts in a new Tab:
Tools > Extensions > click to highlight View Source Chart > Options > click checkbox
A It doesn't. The browser is making these changes, VSC merely displays what the browser has done with your code. Most common: self closing tags lose their closing slash (/). See this article on Rendered Source for more information.

Ctrl + - Allows Zooming OUT of HTML Chart by decreasing text size.
Zooming out allows a broader view of the document structure.
Ctrl + + Allows Zooming IN of HTML Chart by increasing text size.
Ctrl + 0 (zero) Changes text size back to normal.
Ctrl + F Employs the find functionality. Alternatively, you may use Firefox's Find-As-You-Type functionality (specified in Options).
Ctrl + W Closes window.
Ctrl + S Saves the chart to your hard drive.