Hi sherlocke, it doesn't sound familiar. Could you pull out some information for us:

(1) In a new tab, type or paste about:config in the address bar and press Enter/Return. Click the button promising to be careful.

(2) In the search box above the list, type or paste uic and pause while the list is filtered

(3) Right-click the browser.uiCustomization.state preference and select Copy Value

You can paste that value into a reply.

And/or... if you want to study this yourself, I suggest using the "Scratchpad" tool. Either:

• "3-bar" menu button > Developer > Scratchpad
• (menu bar) Tools > Web Developer > Scratchpad

Paste at the end of the document you find in the scratchpad window, the click the Pretty Print button. This should restructure the long line of text into a more readable list.

Scroll down to 'nav-bar': and check the items toward the end of that section to see what you can learn about that button there. (Mine lists numerous add-on buttons that are not current visible because those add-ons are disabled or have been removed.)

Does that help identify it?

Hello,

In order to better assist you with your issue please provide us with a screenshot. If you need help to create a screenshot, please see How do I create a screenshot of my problem?

Once you've done this, attach the saved screenshot file to your forum post by clicking the Browse... button below the Post your reply box. This will help us to visualize the problem.

Thank you!

Thanks so much for the prompt responses.. Here is the text from the scratchpad. It appears that from the entries on the nav-bar there is one button listed between the home button and the Amazon smile button. There is actually a video download helper and the button that is causing the problem between these. On the list it is just identified as 'action button' followed by a long line of code. I don't know which of the buttons this references. I have included a screen shot with an arrow pointing to the questionable button.

 'placements': {
   'PanelUI-contents': [
     'edit-controls',
     'zoom-controls',
     'new-window-button',
     'privatebrowsing-button',
     'save-page-button',
     'print-button',
     'history-panelmenu',
     'fullscreen-button',
     'find-button',
     'preferences-button',
     'add-ons-button',
     'developer-button'
   ],
   'addon-bar': [
     'addonbar-closebutton',
     'status-bar'
   ],
   'PersonalToolbar': [
     'personal-bookmarks'
   ],
   'nav-bar': [
     'urlbar-container',
     'search-container',
     'bookmarks-menu-button',
     'pocket-button',
     'downloads-button',
     'home-button',
     'action-button--b9db16a4-6edc-47ec-a1f4-b86292ed211d-vdh-tbbutton',
     'com.amazon.amazonSmileOneButton'
   ],
   'TabsToolbar': [
     'tabbrowser-tabs',
     'new-tab-button',
     'alltabs-button'
   ],
   'toolbar-menubar': [
     'menubar-items'
   ]
 },
 'seen': [
   'abp-toolbarbutton',
   'action-button--b9db16a4-6edc-47ec-a1f4-b86292ed211d-vdh-tbbutton'
 ],
 'dirtyAreaCache': [
   'PersonalToolbar',
   'nav-bar',
   'TabsToolbar',
   'toolbar-menubar',
   'PanelUI-contents',
   'addon-bar'
 ],
 'currentVersion': 4,
 'newElementCount': 0

}

That looks like the toolbar from the Video DownloadHelper extension.

• Video DownloadHelper (VDH): https://addons.mozilla.org/firefox/addon/video-downloadhelper/

If you right-click > Remove from Toolbar on the video download helper icon, does the mystery icon go with it?

There is a setting in the Options/Preferences (Appearance) of the VDH extension to show the the main and companion button or only one of the two.

When I removed the VDH button from the toolbar, the other icon remained. I went into the configuration for VDH as suggested and the other icon was indeed connected to VDH. I removed the entire VDH addon and all is well! I appreciate all those who have responded to my post. You have all been very helpful in resolving this problem. Thanks!