I assume that with simplify page you mean reader view? This feature requires a special layout of web pages to work.

• https://support.mozilla.org/en-US/kb/firefox-reader-view-clutter-free-web-pages

• https://dxr.mozilla.org/mozilla-release/source/toolkit/components/reader/Readability.js#97

See also:

• https://addons.mozilla.org/firefox/addon/reader/

Hi cware, the Simplify box on the Print Preview screen prints the Reader View, so it should appear when the Reader View button is available in the address bar for your page.

cor-el has provided some links about Reader View, but I don't know whether there is a clear document on what HTML structures allow or prevent Firefox from using Reader View on a page.

Thanks jscher2000, First, for the clue that "Reader View" and the "Simplify page" option on the Print Preview are related, and second that there might not be a clear document that explains what HTML structures allow Firefox to use Reader View on a page. I've never noticed the "Reader View" icon as explained by cor-el in his/her response but I often use the "Simplify page" checkbox if printing a page that's overlaying text, obliterating things, most frequently the URLs of links, making the printed output practically unreadable.

I will look closer at the code on the pages that render a functioning "simplify page" checkbox and those that don't, to see if I can garner any clues about what might cause that feature to not work.

Interestingly, the Firefox Help, "Reader View" page itself has a greyed out "Simplify page" check box.

Note that the DXR link shows what elements and what sizes trigger Reader mode.

• https://dxr.mozilla.org/mozilla-release/source/toolkit/components/reader/Readability.js#97