Yeah. Most likely they dynamically generate new modified pages. There must be a JS variable or function that gets the current line under mouse pointer. Anything I learned of JavaScript was far enough back that I've forgotten. It wasn't much to start with. :)
To A Guy, yes there are quite a number of highlighting tools available. They serve a purpose no doubt. But they're simply not a tool to make it easier to read large blocks of text. They're a traditional highlighter.
MilesAhead, I think you understand what I'm after. And yes, it would be best if it were a feature of the operating system so that it could be used on any block of text in any program. Whether it be in a word-processor or on a webpage in a browser, or even in Windows help files.
Interestingly, in that JS bin example, if you use your scroll wheel to move down the block of text, the highlight line doesn't follow the pointer. It becomes out of sync. Which would be problem.
But again, this is only a means of embedding the feature into a webpage. Not system wide.
Good discussion guys. Thank you.
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