Mysterious highlight in emacs

Question

Recently, I change my laptop from old Thinkpad to newer laptop with much larger touchpad. I've found that I frequently touch the sensitive touchpad while I'm using emacs. And with some mysterious combination, very often there will be a highlight appear on the emacs buffer. The highlight is persist. Cannot be removed by navigating cursor or mouse click. It's not emacs selection mark. The only way I can remove it is to close the buffer and reload the file.

This is very annoying. Anybody know what is it, how to remove it, and best if I can prevent it from occur in the first place.

Answer 1

It's the secondary selection. Clicking and dragging sets the primary selection, and middle click pastes from that selection. Holding alt while clicking and dragging sets the secondary selection, and M-mouse-2 pastes from it. Very few applications use the secondary selection any more, but it's quite handy when you have two things to copy and paste. See section 12.3.3 Secondary Selection in the Emacs manual for more information.

There's no command to cancel the secondary selection, but if you left-click with Alt (M-mouse-1), it'll make the secondary selection empty.

Answer 2

I use package disable-mouse:

(package-install "use-package") ; once, if not already installed

(require 'use-package)
(use-package disable-mouse
    :ensure t
    :diminish disable-mouse-global-mode
    :commands global-disable-mouse-mode
    :init (global-disable-mouse-mode))