Shared components used by Firefox and other Mozilla software, including handling of Web content; Gecko, HTML, CSS, layout, DOM, scripts, images, networking, etc. Issues with web page layout probably go here, while Firefox user interface issues belong in the Firefox product. (More info)
Bugs involving conversion to html or plaintext, either during saving or during copy/paste. This component is NOT for general copy/paste bugs, for bugs involving save dialogs or writing to files when saving, or for I18n-related bugs; only for problems with the actual text which is saved.