LeftMouse focus window without moving cursor

Question

Is there a way for clicking on a Vim window to focus that window if inactive (without moving the cursor), then move the cursor if the window is already active?

Here's what I've got so far:

function IsWinFocused()
    return getmousepos().winid==win_getid()
endfunction
noremap <expr> <LeftMouse> IsWinFocused() ? '<LeftMouse>' : '<LeftMouse>`m'
augroup leftMouse
    autocmd!
    au BufLeave * mark m 
augroup end

Which leaves a marker behind as you leave a window, then comes back to it after rejoining the window.

But this isn't ideal as you have to have unfocused the window since opening it in order for focusing it to work properly, and if that's not the case it could yeet you into the depths of a file if marker m was in prior use.

Also I'm not a huge fan of seeing the window jump to where I clicked and back every time I focus a window

Edit: using Neovim wrapped in Nvy on Windows 11

Answer 1

Ok, I think I've figured it out. Here's the mappings I've come up with:

noremap <expr> <LeftMouse> getmousepos().winid==win_getid() ? '<LeftMouse>' : '<Cmd>call win_gotoid(getmousepos().winid)<CR>'
noremap! <expr> <LeftMouse> getmousepos().winid==win_getid() ? '<LeftMouse>' : '<Cmd>call win_gotoid(getmousepos().winid)<CR>'

It checks if the focused window is the one under the mouse, and if so it left clicks as normal. If the window under the mouse is not the one that is focused, it calls the function to change the the current window to the window under the mouse. This couldn't be done with a normal <exec> command because you can't change the cursor position from within the <exec>. It had to be called using <Cmd>.

Answer 2

You can set the option mousefocus

:set mousefocus

When you move the cursor on the window the window is activated but the cursor is not changed (not exactly what you ask but close).

You can use the mouse wheel to scroll the window.

Remark: It seems that it doesn't work yet in nvim-qt see the following answer for more details.

Remark: Although mousefocus is not working mousescroll is. This mean that you should be able to scroll your buffer by using the scroll button of your mouse when you move the mouse pointer over the corresponding window (again not what you ask but a consolation gift)