I am trying to create a popup window that opens automatically when you scroll over certain text, (e.g., to provide a definition to the terms scrolled over). Help!

What is the URL that you're using for the image file that's the rollover image?

all I had to do was expand the HTML Snippet box

by doing so, you just create static/dead zone on your web page; meaning anything active such as hyperlinks inside the html snippet box will not be accessible.

correct way to implement anything is to have control over iweb.

however, you have little to no control of what iweb does, but it can be done when you have control and know how iweb work.

have a look: http://temp.cyclosaurus.com/revolving/Blank.html

the example is done with javascript and my own iweb widget.

The OP decided to use the rollover image route as suggested by OT. In actual fact the original request appeared to be for a tooltip with explanatory text.

The method that I suggested at the begining of this post uses the title attribute in a hyperlink tag to achieve this and doesn't create a dead zone...

http://96.0.63.10/iWeb-Test/Tooltip-Text.html

The tooltip for an image description uses the same idea with the text in the title attribute of an image tag...

http://96.0.63.10/iWeb-Test/Tooltip.html

On the same page is an example using a span instead of a link.

None of these require javascript or a knowledge of iWeb widgets.

I am trying to create a popup window

that was part of the OP's original post. read the OP's posts in this thread and you find there was no mention of tooltip from the OP.

in fact, you were going on and on with html snippet, but failed to mention of it'st dead zone as you did in this thread: https://discussions.apple.com/thread/3512742?answerId=16806199022#16806199022