1644946 - A B2 click on the scrollbar pastes buffer content into a text box

Status: NEW

(Core :: DOM: Editor, defect)

Description

[Jeffery Small]

User Agent: Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:77.0) Gecko/20100101 Firefox/77.0

Steps to reproduce:

Xubuntu 19.10
Firefox 77.0.1 (applies to past versions as well)

Linux, unlike Windows, has an unnamed buffer holding the current selection. This can be pasted elsewhere using B2.

On sites such as MeWe or Facebook where there are comment text boxes in the page, if I B2-click on the scrollbar gutter to move to a particular position, the page scrolls, but the content of the selection paste buffer is also silently and automatically entered into one of the text boxes which doesn't and usually isn't displayed on the screen. This happens on MeWe if I first click (make active) a particular text box. On Facebook, this happens consistently, so I'm assuming that Facebook is somehow making some random box active without user intervention. The problem is that when I want to exit the page, I'm constantly presented with the message:

"This page is asking you to confirm that you want to leave - data you have entered may not be saved."

because of the text that was inadvertently pasted without my knowledge. Most time I can't even locate where the text was pasted so I've learned to just ignore the message. This is extremely annoying.

I've gone to other sites with things like contact forms and tried to reproduce the behavior there, but haven't been successful, so I'm not exactly sure what the difference is and why it's so prevalent on FB and MeWe.

My middlemouse settings are:

middlemouse.contentLoadURL: false
middlemouse.openNewWindow: true
middlemouse.paste: true
middlemouse.scrollbarPosition: true

I have my scrollbar on the left (3) but I moved it back to the right (0) and tested and the same thing happens, so the position of the scrollbar is not an issue.

Actual results:

B2 on scrollbar pastes content into text box on page

Expected results:

B2 on scrollbar should only affect scrolling and not the page content.

Comment 1

[Jeffery Small]

By the way, I tested this in Safe Mode and it still happens, so it appears to be native to Firefox.

Comment 2

[Andrei Purice]

Hello,
I was able to reproduce this on the latest Nightly 79.0a1 (2020-06-15), beta 78.0b7 and release 77.0.1 versions, on Linux Ubuntu 18.04.4 .

Setting a component for this issue in order to get the dev team involved.
If you feel it's an incorrect one please feel free to change it to a more appropriate one.
Note that the issue is not reproducible on Chrome.

Comment 3

[Henri Sivonen (:hsivonen) (on vacation)]

For me, clicking the middle button in the scrollbar gutter (where a left click would scroll) does not scroll for me and only pastes. (The paste goes to where the text insertion point is--not to where the mouse cursor is.)

Tested Nightly running on XWayland in Wayland session on Ubuntu 18.04.