For bugs in Firefox Desktop, the Mozilla Foundation's web browser. For Firefox user interface issues in menus, developer tools, bookmarks, location bar, and preferences. Many Firefox bugs will either be filed here or in the Core product. (more info)
In Mac apps, command-Delete should delete the text from the insertion point back to the beginning of the line. This doesn't happen in textareas, text inputs, the address bar, or anywhere else in the UI.