When openning netrw in split view, the opened buffer I'm still editing clears when I click a line number

Question

Wondering why this happens, if it is a bug or supposed to happen?

Steps to reproduce:

1. open vim,
2. split two windows, one with netrw and another with few lines of text (line numbers enabled).
3. As both of them are open, click any number on the line numbers column, the buffer will clear.

The interesting part is, this doesn't happen on NeoVim.

Answer 1

I've been able to reproduce this, and here's what's happening.

Setup

1. Open vim
2. Type a few lines of text
3. :Sexplore
4. With the focus on netrw, click on the buffer with text (esp. on the line numbers).

That buffer switches to a new buffer (generally named after the line you clicked on).

Why?

netrw maps <LeftMouse> to call the scriptlocal function NetrwLeftmouse(1). This function is responsible for editing the files you click on. It tries to abort if you don't click in the window (if ... || v:mouse_win != winnr()), but I believe by the time this executes the mouse window and winnr() have been aligned (the mapping actually performs a regular <LeftMouse> first, so focus has already changed).

The function happily carries on and edits a new buffer. <C-o> is sometimes enough to get you back, but because the function uses NetrwKeepj, the jumplist doesn't change, so <C-o> may not suffice.

Solutions

1. Don't use the mouse in netrw (easy to give up, but might accidentally still get you). Combine with unmapping the mouse keys in netrw (in ~/.vim/after/ftplugin/netrw.vim for example) for maximum effect.
2. ??? This would require a serious patch for a strange edge case, and I'm not quite sure how to do it yet.