HOWTO: quickly restore a deleted bookmark in Mozilla Firefox

If you have accidentally deleted some bookmark from your Mozilla Firefox bookmarks collection, you can quickly restore it. No need to close the Firefox browser and restore backup files manually.

1. Just open the bookmarks library: <Ctrl> + <Shift> + <B>
   1. (sometimes (e. g., in GNU/Linux), you should use another hotkey: <Ctrl> + <Shift> + <O>);
2. press <Ctrl> + <Z> once;
3. you can now check if your favorite bookmark is back (just check the "Bookmarks" menu, or by checking "All Bookmarks" → "Bookmarks Menu", or by using the "Search Bookmarks" feature).

Notes.

1. <Ctrl> + <Shift> + <Z> performs a generic "undo" function; therefore, it can undo not only bookmark deletion, but also bookmark addition or edit operation;
2. if you press this key combination several times, it will undo several last bookmark changes (though I'm not sure what's the depth of this "undo queue");
3. don't worry either if you've undone some useful bookmark changes: there's also a generic "redo" key combination: <Ctrl> + <Shift> + <Z> (or <Shift> + <Ctrl> + <Z>, if you prefer);
   1. sometimes (e. g., in MS Windows), there's also another working "redo" hotkey: <Ctrl> + <Y>.

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Last updated: 2017-03-21

HOWTO: find out the PDF.js version built into Mozilla Firefox

To find out the version and build number of PDF.js (built into your installed version of Mozilla Firefox), you should visit a specific URL (if it doesn't work, just try to copy-and-paste it):

• resource://pdf.js/build/pdf.js

and look patiently at the beginning of that page.

E. g., for Mozilla Firefox 38.0.5 we can get the following:

...

PDFJS.version = '1.0.1149';
PDFJS.build = 'bc7a110';

...

(To view more of its internals, just visit resource://pdf.js/. Note: if you browse through that, the address will expand to a specific path pointing to some file inside some library-archive of Firefox, e. g., jar:file:///path/to/firefox/dir/omni.ja!/chrome/pdfjs/content/build/pdf.js).

Links:

• PDF.js - Wikipedia
• PDF.js on GitHub:
  • Homepage
  • Project