[QUOTE="Robert"] Seems i mistakenly thought Firefox would allow me to step thru HTML code and see what happens as the screen gets painted/rendered. Also, it allowed me to edit the code and re-start so to view results. Definitely NOT in FF9 (hell, its editor does not even allow one to delete a line of code). So,what did i use?[/QUOTE] I typed the following into Seamonkey "Composer" window, with the source tab clicked. Then, clicked preview tab to see what it looks like. But there's no single step in there. The HTML is rendered instantly. If you were single stepping code, that kinda sounds like Javascript or something. This is the sample HTML code, copied from some site, that I was using as a test. ******* <html><head> <meta http-equiv="content-type" content="text/html; charset=ISO-8859-1"> <title>Hello World!</title> </head><body> <p>Hello World! </p> <p>Huh, <em>that's</em> not so tough. Now let's check out. </p> </body></html> ******* Perhaps you were using a Javascript IDE or debugger tool of some sort, installed as a plugin in your browser. Paul