What is "virtual control board"?

An external application? An add-on for Firefox?

Never heard of that before.

"virtual control board" - it is a picture, looks like a circle with the dot inside and arrows up an down, sometimes left and right, which resembles a "control board" of a recorder or a TV, etc. It is not an addon, I do not know what it is, I never installed it,

https://prezi.com/vlssr9gqwqfz/virtual-control-board/ Is that what you are referring to?

If so, how does that relate to Firefox support?

no, it is not it, it appears in Firefox, if you point the cursor to it, it shows a menu of Firefox.

and it happens that the mouse cursor moves mostly to the left

Never seen anything such as that in Firefox. Can you grab a screenshot of it?

And maybe another that shows that "menu of Firefox"?

See this support article. How do I create a screenshot of my problem? It is best to use a compressed image type like PNG or JPG to save the screenshot and make sure that you do not exceed a maximum file size of 1 MB.

Then use the Browse .... button below the Post a Reply text box to upload the screenshot.

You have my curiosity piqued as to what that is.

Are you talking about the auto-scroll button that opens if the middle-click in a web page?

• Tools > Options > Advanced > General: Browsing: "Use autoscrolling"

Probaly it is the autoscrolling button, my mouse is only 2 keys, not 3. I unchecked autoscrolling now (only smooth scroll is left). This virtual button looks very much like cor-el logo, only it is round and it has black circle in the middle and up and down arrows, sometimes left/right ones. But why my cursor can move to the left?

I am affraid I can not make a screenshot of that virtual button as you move cursor of the mouse (to make the screenshot) it can disappear

You don't have a Prnt Scrn or prt sc button on your keyboard? Usually to the right of the F12 key on the top row of keys.

Did you try to disable this feature in Options/Preferences > Advanced if it is currently enabled?

• Tools > Options > Advanced > General: Browsing: "Use autoscrolling"

Yes I unchecked autoscrolling after reading cor-el message, and I do not see that virtual button, but still the slider (on the right) may return very fast up after I pull it down, or it can shift to the left-down when I move it in another direction, maybe the mouse pad is dirty but I wash it periodically