How to restore Most Visited bookmark folder in Bookmarks toolbar

How to restore Most Visited bookmark folder in Bookmarks toolbar

1. Visit about:config page in browser

2. Find the preference "browser.places.smartBookmarksversion" 

3. Double click on it and enter its integer value as "0" (zero)

4. Restart the browser

Photoshop Portable - Another instance already open

Delete:

PhotoshopCSPortable.ini

found in:

..\Photoshop CS Portable\Data\

How to disable the new "Website is now in fullscreen" message in Firefox

To stop  the new "Website is now in fullscreen" message in Firefox, do the following:

1. Open to about:config in your Firefox
2. Search for full-screen-api.warning.timeout
3. Modify value from 3000 to 0 (zero)

EDIT: Beware that this feature has been put in place to protect you from phishing attacks that mimic Firefox's menu and UI as /u/Syl0x points out 

You can also try using "Disable HTML5 Fullscreen Alert" Firefox Addon found here.